http://pages.ebay.com/help/community/png-user.html

5.2 Binding Bids. Except for items listed in a 
category under the Non-binding Bid Policy, if you 
receive at least one bid at or above your stated 
minimum price (or in the case of reserve 
auctions, at or above the reserve price), you are 
obligated to complete the transaction with the 
highest bidder upon the auction's completion, 
unless there is an exceptional circumstance, such 
as: (a) the buyer fails to meet the terms of your 
listing (such as payment method), or (b) you 
cannot authenticate the buyer's identity. 
5.3 Fraud. Without limiting any other remedies, 
eBay may suspend or terminate your account if we 
suspect that you (by conviction, settlement, 
insurance or escrow investigation, or otherwise) 
have engaged in fraudulent activity in connection 
with our site.