Getting screwed over on a payment for a parts purchase?

if you show yourself to be a deceitful person then you have what's coming to you. I'm sure any employer would want to know if their managers were conniving and dishonest as well as vindictive and peddled in retaliation.

I gave him several options to do right and come to an agreement as adults. he lost the ebay transaction so he decided to go after me publicly and endanger my livelihood. when called on that and asked to back down he was childish and disagreeable.

play stupid games, win stupid prizes.
The place I just left had what is probably the current standard HR employee policy/code of conduct. Your behavior outside of the company still reflects on the company's reputation, social media posts, public interactions & behavior. They don't want or need prospective customers/clients etc. thinking, "if this is the kind of assclown they're willing to hire &/or employ, I'll move on", it's not fair to the rest of the employees either...