Ten bucks? Familiar with the saying "you're only as good as your word"? Essentially, this guy's word is worth a measly ten dollars.
J_K's not out any money, but a deal had been made. I guarantee if something like that happened on these boards to one of you giving J_K flak, there'd be some bitching going on.
Had it been me (and it has been on occasion), I'd go with the deal that was made first. It's just good business.