Deposit left for car, buyer vanished, now what?

Problem is I really don’t get to keep a free $600. Anyone who has tried to sell a classic car in the winter knows why. After dealing with a bunch of “I’ll buy it if can you store it for the winter” people I’ll be lucky to get $2k for it. Last time I tried it I got so fed up I traded the car to a friend. Come spring, I started getting constant emails from people looking at the old thread asking if the car was still for sale. 8 months later. I asked them where they were last winter, LOL.