Trying to pull any B.S. will not work out in his favor. I'd say the balls in my court.
If I were you...I would have his deposit ready in cash in my hand....as soon as he tries to change the agreed price, pull out his deposit, hand it to him, and ask him to turn around and go home....no arguing, no compromise, no negotiating .....
No one's going to drive 8.5 hrs then go home empty handed....