There is too many official traders as it is. I know you want one more for convenience but some consideration should be given to the narrative and the state of the gameworld we are in in this act.
If it was up to me the only trader would be the halfling in the temple, because she is the only one that has actual trading routes available - i.e. some way of offloading the gear you sell to her and replenish cash.
Of course, that will never happen and all trading, money and economy will remain completely insane and absurd - just for convenience of some players.
