Posted By:
EricHere's another option.
Don't give him the satisfaction of getting the card for $10 less. Tell him to send it back to you, and you'll refund him the check.
Block him from ever bidding on your auctions as was stated earlier, and then resell it on ebay. You'll probably get the same amount back without the hassle. In your auction, you get one free pic when listing. Then in your description, add the pic from your website in HTML coding. That way you can list pics for free.