If you want the auction to continue, just tell the person whoever wins the auction is the one who gets the item (at whatever price it is when the auction ends).
Looks like you made the mistake of doing an auction, and now you want a BIN. You probably can cancel the auction, and set a BIN price, but you have ruined "the spirit of the auction" since that's what you chose for this item. Your the seller, you can change your mind, but don't do this too often, because buyers don't like it.
