Audiogon recommends that both parties try to contact each other within 3 days of the close of an auction. If one of the parties does not respond within 7 days, then the other party may consider it a defaulted auction.
If the Buyer does not respond within 7 days, you may offer the item to other bidders or relist the item in a new auction. You may also consider leaving feedback for the Buyer to make a public record of his defaulted bid.
While it is true that placing a winning bid is a legally binding contract, there may be mitigating circumstances to consider before deciding how far you want to pursue the situation. Firstly, if a Buyer is already causing such problems, then the forced transaction may lead to even more problems. Secondly, it may or may not be worth your time and expense to contact legal athourities to seek enforcement of such a contract.
Generally speaking, we recommend that Sellers avoid problematic Buyers as soon as a problem is apparent. Bidders who default on auctions should receive feedback from the Seller so as to create a record of their actions.
Need more help? Feel free to submit a support request.