How did you know I could be bought for a lunch?
Seriously, I had a *friend* whom I did loads and loads of repairs for, often in exchange for a hamburger, cuz I figured the poor guy could use a break. But I eventually got tired of his using my nearly free mechanic work for his flipping side business. It got to where I'd tell him "if you're going to keep this I'll fix it, but not if you're going to flip it". Then he'd say he's keeping it; I'd fix it; and lo and behold, I'd see it advertised some time later. His last job cost him full market rate...
and that was the last I heard from him.