How about Strong Boxes? They could be sold at banks or, if you prefer, special vaults, but that'd be kind of a hassle to implement.

Regardless, they could be about the size of a "Big ole Pack Sack" Or whatever the hell that thing Griff sells is called. They could have the "no limited equipment" restriction on them, and retrieval could work just like a bank. For example:

Valguarnera goes to the bank and types 'b strongbox'. The banker gives him a strongbox, he puts in all his shiny red dragon gear, then gives it back to the banker. 4 weeks later, Valguarnera returns to the bank and wants his red dragon gear, so he types "retrieve strongbox" or whatever. He pays the banker a small fee (like, 10 copper per level maybe?), the banker gives him his strongbox and Valg gets out all his keen red dragon stuff.

So, maybe there's a one-time fee of 1,000 copper to buy a strong box and a 10 copper per-level charge each time you get it out? Or maybe that's a little steep...Heh. Anyway, that's my idea.