Use Mutual Cancellation if the buyer seems friendly and sane. He will be able to leave feedback and Detailed Seller Ratings.
If you get a bad feeling about the buyer, wait four days from 'purchase' (96 hours) and open an Unpaid Item Dispute. If he does not pay, he will not be able to leave feedback and Detailed Seller Ratings.
In both cases, you are freed from the transaction and get your FVF back.
