Not very respectful, I agree. But still, you can’t allow yourself to get annoyed at someone else’s actions. You can only control your own actions.Beating me up on pricing then selling for double doesn’t fly.
You could look at it and say, in an otherwise good friendship, why not be friends over a mere $500. Friends are harder to come by than $500. From your side, you’re thinking, “he shafted a friend for $500!!). And from his side, he’s probably thinking, “being unfriended for $500 shows how much he values the friendship”!!!
But I certainly sympathise with you. If it happened once, then I’d probably resist bargaining with that guy again in the future. And just stick with your price.
You could always say, “if you ever sell it, I want it back at the same price or if you do sell at a profit, give me half the difference”.
I’ve done that at times, if it’s really been a cheap price that I’ve sold to someone for.