The best idea... is to actually not have wards at all, but retainers that you summons from the bells only, and when you search (from any atheryte, or summon bell) you can purchase items directly from there and its delivered to the retainer of choice and you can pull the item off the retainer.

All worlds can be connected with this retainer thing, and this prevents a "maximum" amount of players in a certain area, while fulfilling the feel of an AH, reducing the time needed to search, market wards crashing, and more...