I was unintelligent and posted an item on Craig's List for an amount that I thought it might move. I get a bite immediately and the guy haggles further to get me to include the shipping. My wife then hears what I've done and looks up on the internet a similar item listed for oh, say, 35 times more. How obligated am I to go through with the deal? The guy knows the true value of this item, where I did not. Now that I do, is it too late to renegotiate or am I obligated to receive his money...