No the dealer doesn't have to sell it, but standards of business practice would say the dealer is wrong. Of course, there are always exceptions. If something is listed at a ridiculous low and wrong price, it would be considered a sort of theft if you bought something at that wrong price. The seller doesn't have to honor a reasonable error. Now, the question is, does that translate over into an "error in forgetting the reserve". I believe that generally eBay would say no. There was plenty of time and opportunities to withdraw the offering before it was too late. And is in general, in violation of eBay seller rules. And is this slander by the buyer? Of course not. It's the truth. They need to give him $4000 with a gag order. And sell him the car. edit: oh, and get rid of the person that set the auction up on eBay, those mistakes are getting expensive...