I'm not sure I agree with you posting this situation and potentially damaging his rep,under the circumstances you listed.It is sometime difficult to make a judgement call about whether to post or not.I would say unless your 100% sure e-mail a moderator for an opinion or post the situation without the names mentioned,so as not to damage a rep if you wind up being in the wrong.If what you outlined is totally correct,it sounded like he may not have been totally sure about the value himself.You stated he sent a tentative offer,even if it is possible to get 175.00,maybe to him it is worth 100.00 as an offer.As you said yourself,you accepted and sealed the deal.I've sold many knives for less than what I may have been able to hold out for,just for some quick turnaround cash.I don't belive a 100.00 offer was by any means lowball or unethical.If he new the knife was worth 1000.00 dollars and offered you 100.00,then maybe he would not have much integrity,but then you have to know for sure he new he was taking advantage.Honestly;I don't see what the guy did wrong,there is not even a source that gives you a value that is engraved in stone,all these thing are based on supply and demand.The item is worth what someone is willing to pay and not a penny more. Just my two cents,Ralph