I've been looking to start learning how to play the piano for awhile.
I don't want to get started with a teacher(parent's money) or buy a more expensive keyboard(also parent's money) when I'm not totally sure I'm going to go through with it though.

What could I get that's really inexpensive(under $100 new/used) but I could still learn on for a month or two?

I realize they're really limited and unlike a real piano or weighted keyboard, but I want something to show for before I ask my parents to put money down on this so they know it's not going to waste.

If you have a computer, you can invest into a cheap Masterkeyboard and let your PC generate the sound.

At your budget however, you won't get a decent key action. So be careful: I started off with a real cheap MIDIStart 49-key Masterkeyboard. It was okay for the very (very) beginning (first few months), but it frustrated me quite fast. Especially since a had a teacher with a high-quality grand and was not able to near-decently play on this instrument what I had practiced at home. It made me quit my lessons.

I resumed however, after I bough a decent DP.

At the $100 price point there is not a lot of difference. A 61 key Casio will do. It is better to buy a used one for $50 or $80 because you can re-sell it later for almost that and only loose 1/3rd of what you paid. CHeap keyboards do not hold their value

The other thing you need is a book. Get one that comes with a CD and DVD. On the Adult Beginner's forum there is a long thread for people wh are using "Alfreds #1" (and nos. 2 and 3) FInd that thread and ask about that book there.

I'd say that a good goal would be to finish the first book, No. 1. Doing that would prove to all involved that you are serious and then you could replace the keyboard.

I started on the Casio LK-100, which costs about $100. Impulse buy at Target.

You might want to get an entry-level keyboard that's velocity-sensitive, but I doubt those are available for $100...

I put a lot of thought into my recent purchase. I know I was interested in learning piano and wanted to go the cheap route before I invested money into something I wasn't sure I would stick with. I couldn't really go that cheap though without sacrificing too much that would hurt me in the long run. I would suggest you look for a USED Yamaha DGX-230 / Yamaha YPG-235. They are the same exact model just different numbers for where they are sold. For $300 I got it NEW with stand, power supply, and headphones. So a used one you should be able to find in your price range. Check craigslist, ebay, and wherever else.

My opinion is that it's great so far for me as a beginner. It has 76 piano style keys. They aren't weighted but its got the graded hammer system that allows different amounts of key press volume like a piano. You can add a pedal as well. It's got all the keyboard bells and whistles too. It's a really nice piece of equipment and I'm loving it. You can go much further than a few months with it. I got the alfreds book 1 with it and I havent looked back. It's a great way to start.

@winstonplatt
I don't know where you live, but maybe leasing/renting an instrument can be an option. Piano dealers here in Germany allow for leasing acoustic and digital pianos. When you finally decide you are serious about this and are ready to invest time and money you can buy the instrument and get your leasing payments credited on the purchasing price.

The major advantage would be that you can get a realistic evaluation whether the piano is your thing or not.

@Martin
You can get velocity-sensitive master keyboards for less than 100$ - however, you need a computer to produce the sound. I had a Mac Laptop available, so GarageBand was the virtual instrument I could use without any extra costs. I don't know, if there is suitable freeware or useable demo software available for Win or Linux though.

I've got a Macbook Pro. Maybe I could go the master keyboard route. What would you reccomend?

You could take a look into the M-Audio KeyRig or KeyStation product line (the latter being above the 100$ budget). Miditech is a german manufacturer with similar products.

However, my former warnings apply - these keyboards are veeery basic and have not much in common with a decent digital piano's hammer action (and even less with an acoustic piano). Also mind that these keyboards have no provided sustain pedal (although they have an input jack so you can add a pedal later).

http://www.m-audio.com
http://www.miditech.de/produktee.htm

High-quality master keyboard with hammer action are in a common pricerange (above $1,000) with good digital stage or home pianos and are more suited for professional music production.

So is there a significant difference between a "velocity sensitive" keyboard like this: http://www.m-audio.com/products/en_us/KeyRig49.html and one that has no velocity sensitiveness at all?
It looks like i'll go with that one though as its powered by just USB and I've got some pretty good headphones($400 range) so at least the sound will be decent.

Very significant. With no velocity sensitivity, you will lose control of ALL dynamics. The sound the key makes will be the same volume and timbre no matter how hard or soft you hit it.

I agree with other poster on renting. Most places will let you apply rental charge to new purchase if you decide to buy so you wouldn't lose anything. That would allow you to get something that has a more realistic piano key touch, as opposed to something that feels like a toy.

I'm sure you will want to have control of how loud notes are played. Actually even later after you buy an 88 key weighted digital piano you might still have use for the littel 49 key m-audio keyboard. They are good for editing music in Garage Band and the synth action and wheels make it better than a DP for playing sounds like guitar or saxophone. I gues the good thing is that this is different enough from what you will end up playing the youwould not have duplication

Since you are trying to keep cost down, there is always the used market to consider. Craig's List has a lot of stuff you could consider. The only thing you need to be careful of is paying too much for a used DP. Many sellers ask more than original retail so you need to know how much the piano retailed for new and offer them half of that or less.

We actually have an old "Angelus"(I think) piano in a room connected to our garage. My dad only paid $300 for it though, so I'll have to see if it's worth learning on. I think it's in good repair (though definitely needs a tuning).
It's kind of cool because it's got slats on the front, right in front of where you would sit, so you can look in and see some of the hammers striking the strings.

I'm still going to get a keyboard first though, might wanna play around in garage band besides

Winstonplatt, I've sent you a private message you will find in the drop down of "My Stuff".

It really depends on what you're looking to do with your new skills. You can make music with a keyboard connected to your MBP (my sister has the m-audio keyboard connected to her Mac), and even the most basic 61-keyboards can make some great sounds (if your interests are garage band or playing gigs). On a keyboard, you can work on fingering, chords and quite a bit of theory on making music.

The skills you acquire on the keyboard aren't generally considered "piano" skills though. If you're interested in piano skills, most people on this forum would encourage you to get access to a good acoustic or digital piano and stay away from 'keyboards'

winstonplatt, My message is there, now. BTW, I would agree with danGIMP. If you like the work of learning, you WILL want a decent DP or acoustic instrument. I have both now, but find the 49-key controller the best compromise solution for practice when traveling.

Yeah I definitely plan on upgrading if I get into it. My dads always wanted us to take music lessons and I think he would be willing to buy me a good DP, or maybe our old piano will be decent enough after a good tuning.

What program should I look into for producing the best sound? Is there something that will just take the signal of whatever key I play and turn it into an actual piano sound?

You mean like TruePianos, Pianoteq, or Ivory? There are many such programs to choose from. The advantage of TruePianos and Pianoteq is that no fast hard drive is required, whereas e.g. Ivory needs quite a bit of HD space.

Generally, I think the advantage of software pianos is that they are more sensitive to tiny variations in technique than the builit-in digital piano sounds. It's a much better learning experience and they are more addictive to play.

"Best?" That could get expensive. How about "best value"?

If the computer is a Mac then Garage Band comes with some pretty acceptable piano sounds. Just use that, it's already installed and won't cost anything and is "plug and play"

But if this is a Windows PC. And I assume you wan to keep the cost below a couple hundred dollars. Some of the popular ones are

Pianoteq
True Pianos

You can find a long list of leads to track down here
http://purgatorycreek.com/
(from the above URL click Piano Shootout -> software samplers)
But some of these are old versions, some new stuff is not there and many are to expensive. Listen to the demos and Google the names on the list

I like Sampleltekk's "black grand close" and the price is reasonable ($49) but be warned that to use a product like that is a lot more complex then a "packaged for consumer use" app like Pianoteq. There are two layers or software that you must install before you can use a "bare" sample set. but it's easy to find Sampleltekk web site and listen to the demo MP3s. Most of these products have MP3 demos.

Pianoteq will run in demo mode, you can try it even without a keyboard

Shopping for software is maybe even harder then shopping for a physical keyboard. There are so many on the market that doing a evalation of them takes weeks.

Then you need good speakers and maybe a good audio USB audio interface. And almost certainly (if yo have a Windows PC) you need audio drivers.

In the end most people just get a self-contained digital piano.

Okay I'll probably use Garage Band. Just tried it out and it's pretty good. When I tried it at the apple store(they had one computer connected to a MIDI keyboard) it must have been set to make "electric keyboard" instead of "grand piano."

And with the link there they had a sample for a Steinway preset garage band can make with the "Jam Pack" which you get separately. Probably going to get that, sounds really nice.

The Orchestra Jam Pack has a couple pianos in it but also 1000 other things. The piano is only "OK". The Apple Jam Packs at $99 each are great deals if you need even half the sounds but not such great deals if you need only one sound. If you want to be able to play violin, trumpet, Oboe and Pianos then buy it. I literally adds a full orchastera of sounds to GB but the pianos are only "decent"

I think, maybe GB might come with an EXS24 sampler instrument? Logic has it but I forget about GB. If so then you can play those Sampletekk sounds which really are good. prices are on bolth sides of Apples' $99.

See the current thread here about the "DP BSD Project" the MP3 file I sent was one of Apple's Yamaha samples. Turns out the quality was about on par with a Yamaha P120. But I think the sound is better.