Zen items can be lost pretty easily, a downside of having a lot of alts. I only have 12 characters, but imagine someone with, like, 40; they could buy a Become device for one character, forget about the character later on, and then delete the character and the device with it. That, uh... happened to me once, actually. :P
Why not have a "Zen Bag" that would be shared among all characters? It would be used for sharing and holding Zen items among characters.
-When you buy a Zen item, it will automatically be sent to the Zen Bag in an unbound state.
-Character-bound Zen items (not sure if they exist) cannot be placed into the Zen Bag.
-When a character is deleted, all qualifying Zen items will be sent to the Zen Bag. A pop-up should warn about this.
-Any character can deposit/withdraw from the Zen Bag at any time.
Things to Consider
-Should this only apply to items that are bought from the Zen Store?
-How could one abuse this system?
-Whatever else comes to mind.
I'd really like to hear your thoughts on this. I honestly feel like this has been suggested before. XP
EDIT 1: Now that I think about it, maybe Character Bound items could start off in the bag, at least.