sold a "friend" a graphics card

Okay so I've been googling all morning to no avail, so I've gotta turn to reddit.

I live in MN if it matters.

A few months back I sold a coworker a GPU with a promise to pay (just 200 bucks). Since then he has been fired and blocked me on everything so I have no real way to contact him aside from showing up at his door, which would be a last resort.

Basically wondering what my options are. I've got proof of ownership of the card because it's all registered in my name and I have pics of it in my PC. It was a 650$ card and I sold it for just 200 bucks. All I want is the 200 I was promised.

And I can't just eat the 200 dollars. He did also try to get me fired by lying about a bunch of stuff as well. So potentially also a cease And desist for slander? Idk. I just work at a hotel lol

Thanks for any help y'all can provide.