I saw on craigslist someone has for sell a Yamaha YDP-121 for $650. I thought that price might be a little high but was wanting some advice what price it would be worth. Is it a good starter piano my son is 8 years old and is a beginner.

The way to think about it is this: "Is the YDP121 worth $150 more then a brand new Casio PX130?"

Look at the specs of the 121 and 130 and then decide. I looked and my answer is "it depends.".

Don't just look at the PX130. Compare the YDP121 with other new pianos that are both $100 higher and lower than $650 and ask if the price difference is worth it.

The YDP121 certainly meets most people's criteria for a student piano -- weighted hammer action keys and decent sound.

it's a pretty old DP, from 2001, with 32 polyphony and its action is not even graded. if you check specs on new YDP140, you can see YDP140 is far better than YDP121, and costs only about $350 more. so. think twice about it, unless you can get it for less than $500.

I would say that if the purpose of my buy is to get a feeling of a piano, the keys have to be progressive/grade weighted and I would _not_ buy the YDP-121. If progressive keys are not the purpose of my buy I would only give $300 for such an old DP as YDP-121. I would also try to check how worn the keys are by playing a little.

Some people in this forum have said that the YPD-160 is the better (speakers & voices) of the simpler YDP pianos (as YDP-140 is regarded being a little too simple).

I would also take a look at the Yamaha CLP-320 (more polyphony than YDP-160) which might be less expensive than the YDP-160 depending on where you go shopping.