Verbally counter back at $1000 higher than his offer. Let him get all excited and have his agent write up a formal counter at the new price. Then tell him you changed your mind, but you'll do it for $3000 more than that. Let him have his agent write up a new counter. Then tell him you changed your mind again. See how many offers you can get him to write before he gets pissed and walks away...
I sold the house. more than 3x the offer I spoke about when I started the thread. I ended up having 5 or 6 offers on it. I guess I priced it pretty well : )