MEMBER "RDWSP" DID NOT FINISH PAYING BILL

Anyway just gonna let my lawyer figure it out. I am done with this bumm.
I get the feeling you thought this to would be a "yeah, you're a good guy, I'll do this for x dollars" from someone you didn't really know too well, without any sort of signed agreement. And then took a boat or whatever in payment.. this may be very hard for you to win in court, and you might wind up losing money at the end of the day. It might be worth it if you wind up with the car though.
I run a photography business on the side, and I've dealt with **** like this.. didn't take me long before I found some sample contracts online, modified them for me, and made anyone that paid me for what I do, what was expected, and my terms, and sign it. It came in handy a few times when I had someone tell me 'I want ALL the raw images you took at my wedding! I paid for them! I'm calling my lawyer!". Yeah, sweetheart, you signed a contract that stated "I will only release to you for personal use processed images which I deem acceptable ." I never got a call from any lawyer.
You're basically running a business with what you're doing. I'm not saying you need to go get a business license or anything like that... but get an agreement, and make it specific, and vague at the same time (hard to explain what I mean, there may be some lawyers on here that understand that).
I'd hate to see someone not take advantage of your skills, but if they won't agree to something like this, walk away.

Just my two cents.