As per eBay's terms (you'd have to read the fine print) some auctions are legally binding, but car auctions are not.
You can't do anything. In practical terms even with an ebay auction you have to have a willing seller and buyer. You don't have a willing seller. Better luck next time. Complain to ebay. They will tell you the same thing.
Next time he re-listed it, I would bid it up high to win the auction, then give him some of his medicine back. No action against you. Cause eBay would look at the first time he listed it and who won that one. G-man
It is his bad luck for not putting a reserve on it. Make him sell it to you as you are high bidder. He should be more careful. If your bid was a reasonable bid for the item up for auction, I think you can make him stand by the deal. (Retired Attorney)