The person may have had an emergency or something. When some more time passes (like 2 weeks), start ebay's non-paying bidder process. You have to do that to get your fees back any way. I've only had one non-paying bidder and it was an unresponsive person like you may have here. I waited a month, periodically sending reminder emails, then had ebay contact her. She made 2 attempts to pay less than the full amount by personal cheque (which I specified in the auction that I don't accept) and they via credit card on Paypal (which the auction also said I can't accept), then I left negative feedback 4 days after I'd said that I would. Of course, she "returned the favor" and left negative feedback for me saying that I was "hard to deal with".