Alright, been kicking this topic around in my head, and think I may have come up with something that wouldn't result in overly much "server" space.
So here goes....
PC goes to bank(or other Dev team approved locations), in a special "Vault" there is an NPC who manages the storage of items etc. Players speak to the NPC and purchase an item that we will call a Claim Ticket.
Now, in this storage area, or within a specific trigger using the item allows a PC to target an item in their inventory. Variables are then copied with the necessary info (resref/tag etc) of the item being stored.
When the PC wished to "claim" their items, they would use the ticket again within the confines of the vault(or trigger) and the ticket would be destroyed and said item spawned on the PC.
Claim tickets could be traded so the sale of items might be done without the actual item being present(this would be very helpful for the merchants).
My only concern is that it would be difficult to make items that have been altered in some way via the craft appearances function to respawn looking as they had previously.... if that wasn't possible, the player could always be warned in advance.
and there we go, a Storage system that won't bog down the server with countless bytes of database data.
so, what do ya think?