Pretty sure there is no law around this. The guy consensually handed over the money and then consciously didn't pick it up. There's no title, no receipt, no deed... Just a "hey here's some money for a machine, that I'm not gonna take."
If you got rid of it and that guy got a lawyer, pretty sure the lawyer would laugh at him, a judge wouldn't waste his or her time listening to the case and a jury of 12 of his peers would call him an idiot.
Holding it 2 years, Reaching out repetitively, Searching obituaries, looking up inmates....
You're doing way more than would be expected as a seller. I agree with everyone else that says forget about him.

I still lose sleep over this, what ever happened?!!!!

The juke situation is interesting too but I meant with @embryonjohn’s scenario