Had a kinda similar thing happen, but over a phone. Dude needed a phone asap like right that minute, offered me $60, it was up for $130.
Told the guy I'm at work till 4 so I can't get the phone anyway.
Keeps offerering me more money every hour and harassing me to come pick it up asap.
I just ignored him in the end till he offered my $100 then told him I would have accepted that if he hadn't low balled me in the first place.
Then told him to get ʞ©$ɟed.
Sold the phone for $100 the next day to someone else.