If you get no joy, open a non paying dispute 4 days after the sale and go back 4 days later and close it. That way you get your fees back and the buyer gets a strike against their name. Once the case is closed, you are fine to relist. They also can't leave negative feedback once the case is closed. If they leave it prior to closing, it should be removed when the case closes with non payment.

If you just cancel, they may decline the cancellation, which means you lose your fees. They can also leave you negative feedback.

Given there were 2 bidders, you could offer a second chance buy to the unsuccessful bidder. You have to wait until the case is closed prior to doing that though, in case the original buyer fronts up.