I have done a lot of dealing online (nothing X related yet) and have had mostly good transactions. I do have to say, it sounds like the seller really didn't think through the deal before agreeing to it and when he realized he could get a better deal else where, he took it. My stance on on-line trading, once a deal is made, stick with it. If you don't follow through, it always looks bad on the person who broke the deal (be it the seller or buyer). Sure, there is no legal binding contract or anything, but when all is said and done, you don't want to burn too many bridges.