I actually made up an idea about this and posted it in 2 other threads that i left comments in:

City Banks: The City Banks would be to hold all your items, money, crystals and so on. When you walk into the bank it would take you into a zone with in a zone so it would have no issues with storage space. I think that is how it works. You would pay gill for how much space you wanted. Each price would give you a number of slots to hold your items.