Nah, in this case is just a troll, believe me. When you know that there are people in this game with more than 10.000 armbraces and you still don't want to sell it after 5 years, it is either because you don't have it or because you never had the intention to start.
Regarding people selling materials for expensive prices, just ignore them, it happens every day, you don't have to give any explanation to them, just finish the chat in that moment and leave them talking alone. There are people in this game who tried to sell me things like Strength & Honor inscriptions for 10e each one, I'm well aware of the nest of scammers in this game. And there are others that if you don't buy the item at the scam price they want, they try to convince you that you won't find it for less than that price, like trying to make you feel guilty, it's pathetic (happened to me with maaaany greens and golds and they all ended up being wrong). I see good paying 200e for a Jormungand's Thunder due to the conditions that must be met to obtain this green, or 8-15a for a Firebrand (I paid 9a in its moment), but I will never pay 300e for a Drago's Flatbow or Tanzit's Defender for example (I have 3 Tanzit's and I paid I think like 3e and 7e for those, the other dropped to me, and the Drago's I have even given them for free, it's a very common weapon despite what they try to say to scam you). Also I think I sold a Beacon of the Unseen for 5e? I don't remember now, I think it was some price like that, I didn't use the item and didn't care if it was rare, I just wanted to get rid of it to gain inventory space.
In this game, apart from those who are always online 24/7, new people enter every day for a short period of time, so you always end up finding what you are looking for, it's a simple matter of leaving the game open in the background. I'm not even aware of the chat most of the time, I still work from home due covid so I have no problem leaving the game open for most of the day, I leave my "WTB" or "WTS" in the chat and put the game in the background, so I only have to be aware of the whisper/trade box sound, it's "practically" zero effort. Recently I've been buying Shadow Scythes and an user from this forum whispered to me telling me that I was not going to find them -as well as some insults-. I have x10 q9 currently, so again, wrong. It's a rare weapon, but not that rare. And the same thing for every single weapon or material, don't feel pressured by what another player tells you, it's just a game.
So if someone sells for more than what you estimate the item at, they're scamming ? Are you numb, stupid or living in a toddler world ? If you can't put an extra effort in getting 5a for an item you want or an equivalent since this person does accept trade, what's your point beside the fact that you don't really want the item ?