If any of your potential buyers leaned of this they'd likely think you're an utter dick and possibly avoid you in the future. As someone who mostly buys on ebay, crap like that would piss me off to no end, especially if it looked like I would win it. Frankly I'd tell the person to go bid on the item online and that I might cut them a deal on shipping if they win. That way you might provoke a bidding war, getting more than you would have otherwise, and you don't risk annoying your actual bidders.