Items being held at traders for long time (depending on their type, max 3 real time days), get turned into caps. Will get turned into other (more usefull) stuff later, to help traders one more time.
Yeah, the idea is not bad, but it has some potential ways to abuse it. How? It's simple - one could sell his/her almost fully deteriorated weapon (for some caps), and then... voila! It's magically repaired by merchant, and you can buy it back, fully repaired...
i dont think its any good that you have "only" 49 secs to barter
we were looking for almost every useful stuff (raw materials for crafting, armours, pvp weapons, ammo...)