[abyssknight]

I'll agree with the others and say drop this guy without a second thought. That said, if you wrote the contract to include disclosure of source code you should be able to legally ask for it. That said, $2500 is a relatively small amount when we're talking about a complete system with source code rights. Your best bet is likely to file for small claims (usually costs you between $25 and $250 depending on the amount, and you can only file for up to $2500 here in Florida). You likely will not make it to court, and he'll settle. Why? Because everyone fears litigation, especially when they're wrong.

Next time around, write the contract the way you want it to read, and account for failures. Make certain everything is in writing, even if there is a deviation agreed upon by both parties. And above all, get what you paid for in increments and never pay in full before the project is done.

As a developer, I respect the 50/50 plan as well as the hourly one. 50% up front to cover development costs, 50% at the end to ensure I finish. Works like a charm.