I doubt if eBay would "require" much of anything at this point. Here is eBay's policy:

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.

I don't know if this qualifies as an "exceptional circumstance" or not. You should try to remember that the winning bidder did nothing wrong, and was obviously willing to pay a fair price. You set the minimum bid, and he won it for more than that. If he's a reasonable person, he may very well understand that another person's actions in bad faith created a situation that was very unfair to you, and let you out of the deal painlessly, or offer to pay the $51 rather than see you list the chip again. I would take that offer.

Also remember that, while you cannot leave negative feedback for Ms. Soze for retracting her bid, your high bidder CAN neg you for failing to complete the deal. I'd start off by trying to have a rational friendly discussion with him.