If you say no, then you risk getting bad feedback on the sale. However (not sure if you're an e-bay guru or not so forgive me if I'm insulting you), you can appeal bad feedback to the e-bay management, and from what I hear, they're pretty good to work with on this stuff. What I would do is say no & risk the hassle - sounds like a scammer, and those people need to be draxxed. You can also block him from bidding on any of your other auctions.