From what I've seen skulking about the forums, npc's are not something the devs are looking at in the near future, but what about player and guild-made quests?
A player would select the item(s) they want, and would store the item(s) in the trade plinth that they want to give as a reward. Once someone has retrieved your items, the trade would be made through said plinth.
Players would be able to offer only a few (3-5) and be limited to the items they can request and offer (i.e. They couldn't request 30 of the rarest ores), whereas a guild trade plinth could request and offer higher quantities of rarer tiers of items (i.e. rubies).
This system would help build a type of bartering economy, leaving coin to be used for warping. It would also appeal to player who might not have the cash for shops, but they have the skills or desire to hunt for the objects.
Edit: Title changed from "Player and Guild quests" to "Trading Plinths"