This ties up with me learning about brokers. Part of how I learned without the wiki.
Adventure mode:
I had a legendary elf bow/swordsman who decimated all who were against the quest-givers.
I had tons of loot including steel weapons and some armor too large for me.
The best part of it was, to buy more ammo.
I took the weight (with the funny symbol next to the name) in shops as the price of the item.
So what happened was that I sold my steel weapons and armor (not including the weaker steel armor I was wearing) for a bunch of arrows and a new iron bow.
Somehow, I felt something was so wrong in trading and thought it as a bug...
(I'm familiar to roguelikes so I guess that is how I lived far enough.)
Fortress mode:
-Idler Haven-
--Trade caravan has arrived!--
"Hey Urist, we have any brokers?"
"No, I'll talk to em. I'm the best speaker there is anyway, who needs brokers."
"You gotta be one to trade."
"Oh, right. Fine but you go first, I'ma take a drink."
Urist Mc 1 goes off to trade, I find my predicament the same, thought weight was the price, began trading some chairs and tables for a barrel of ale and a leather bin.
"What in Armok's name do you think we are, elves?!"
"Err...the broker is busy drinking away an-"
"Get someone who knows what he is doing! I want a profit on this one and I'm not leaving till I get it!"
*Urist McBroker finishes up and pushes aside Urist Mc 1*
"So...what do we have-. By Litasts bloody finger! We have no trade goods!"
"But we have finely crafted chairs, tables and door-"
"They sell at 20-50 each. The goods we need are over 1000."
That is where I noticed, there was a funny symbol next to the weight.
That was the price of it all.