As suggested in this thread, using a kiosk-search tool instead of an AH.

This would keep lore intact, and allow for further benefits to having a guild trader. The EETC could even be an independent guild, similar to the Mages and Fighters guild, beholden to no faction, and able to do business with all 3.

The EETC would be able to see the contents of every hired Kiosk in the known realms, and show you the location and name of the Trader with the item for sale. You can purchase it directly from the EETC for a small fee, but you must physically travel to that trader and pick up your goods or wait xx hours for it to be delivered "in the next caravan".

This would encourage travel between zones to avoid potential markup, and allow for increased diversity in goods available to those still in the base campaign or Cadwell's Silver to those locals that are not open yet.