I got it back in July on Ebay and the sustain blew out a month ago. M-Audio will only fix it if its from an official dealer, which its not, so I'm screwed. Any other way to fix my sustain? If not, what are some good keyboards within the 400-500 dollar range?

Budget is always a limiting factor. That $500 budget would let you have a good deal on some Casio Privia DPs. Probably you can find a good on-line deal on the Privia PX-200.

Or, you can always wait and save up $200 buck more and get the Casio Privia PX-320 instead. It's more of a "gig"-type or home studio model.

Both the Privia PX-200 and PX-320 can be used as MIDI controllers aside from the usual portable DP use.

Or, you can go for some used/2nd hand DPs. Do remember however, that for $500 bucks, you could already have a brand new DP in the form of Casio Privia DPs. Nothing wrong in getting used, except you don't know the remaining "lifetime" of the parts or when an old used DP would give up on you.
So you might want to consider these things first before going used.

If you must get a new digital piano get one which has AT LEAST 64-note polyphony or MORE (i.e. 128-note polyphony).

Have you tried swapping out the sustain pedal? While anything's possible, its more likely that the sustain pedal died.

Alden

+1 probably just the pedal.

Nope. I have a SP1 and SP2 pedal, both made by M-Audio. Neither will work! Sigh... Any other suggestions?

Open the thing up, and see if the jack is making a connection... maybe something's bent in there.

Yeah..I dont know how to do that. Besides, I've decided to sell it and use the money to help buy a Casio PX-200.