I'm a little confused... What does he 'think' he should owe you for the work? I read where he said he thought he paid for the parts and some labor.. But, seriously is he just delusional or what? How can he expect to just walk away with the car in the finished state? If anything I can see him walking away with the car painted and the trunk full of his uninstalled parts in a worst case scenario - ie the original deal. But what does he really think he owes for the finished car? Hopefully you have a backup plan should he get a bond together for the car to make sure it can't leave with any more of your work besides the 'original' request? I can imagine as soon as it leaves your shop some of the stuff would be sold off immediately with as shady as he is. Just trying to make sure you are protected over losing even more.