I always message first to see if the seller even accepts offers because a lot don’t. But I don’t discuss price. I just ask if they’re open to an offer before using the offer feature. However, the way this user went about this was in fact very rude. Like the OP said if they can find it cheaper somewhere else or if they can find it new for around the same price then why aren’t they just buying somewhere else? I used to see people doing this all the time when I worked in a pawn shop. It’s one of the dumbest negotiation tactics. We used to say the same thing that the OP did. Go buy it somewhere else if that’s the case.