He won the auction for an OSX DVD I had on eBay, but instead of paying for it (and after opening a case about the lateness of his payment) he responds to me a week and a half later to tell me he's not going to buy it because he didn't win a laptop from another auction.

This threw out everyone who had bid for it ( final winning bid was $100) plus all my efforts to try and get him the cheapest shipping from Canada to the Czech Republic. Not too happy and it's completely inconsiderate of him!