I am not sure if this is just my experience or not, but I never see anyone selling old gear on any channel I am on. It may have to do with other dynamics I haven't thought through
Its mostly because the "Bound on xxx" thing, many many many items in this game will bound to account upon equip, dye, convert. etc, etc.
They may have their reasons for every Bound on xxx design, but they are over-doing it in general.
Very simply, raising the VR level cap makes this game more work than fun.