To your "buyer" who I am sure is watching this thread:
Pay the man a fair price, promptly. If you do not, you best expect consequences.
A good, relatively low-mileage running 3FE (forget the other parts) should be worth a MINIMUM of $350.
If he has no coin, and can't return the parts because he has sold parts off of it, it sounds like a trip to the pawn shop in in his near future.
I have never once purchased an item on credit, later came into financial trouble and then decided to effectively steal said item. He might as well have pulled up to your house at 3am, silently entered your shed/garage, and boosted the engine while you slept. The net effect is the same. Until he makes good on his debt, or at the least acknowledges his debt to you (with a specific amount and an I.O.U.), he's a thief. You may choose to reject an I.O.U. na demand prompt payment, but it sounds as if he's trying to weasel out of what he owes you with the bull**** "it wasn't as good as I thought it was going to be" excuse. If that was the case, he should have returned the item. Even Israelis do not barter with balls that big.