I'm thinking of going to my local Apple store, some time next week, and seeing what they can tell me. I would ask if they had an empty case from a display model or something, but I doubt it, since this isn't really the kind of item you would display. Though you never know, it never hurts to ask. Maybe they have a returned one, or maybe someone walked out with the charger, but left the case, or something. Or if I just tell them what I need, they could contact apple and see if they could get some extra cases.
I don't plan on telling them all about the prop part of why I'm looking for one. I've gone down that road way to many times, and it always kills the conversation. It usually goes something like this:
Me, "Hi. I need this part for a replica movie prop"
Staff at store X "Oh, no, no, these aren't mint for that kind of thing, you have to go to a special store for that kind of nonsense."
Me, "No, really it's just a regular item, sold at stores like this."
Them, "Oh no it's not"

(walks away, or gets rooder.)
Then I look around the store a bit on my own, and usually find that exact time, or one like it, setting right there on the shelf. I always want to go show the person, and tell them where they can stick it, but I know that kind of thing doesn't get you any where in life. Plus, you can't teach some people anything, and they will just pass your roodness on to the next costumer, so instead, I just buy the item and shut up. (sorry, got a little off topic there.

)
Anyway's, I'll see what I can do, but if someone else wants to take that ball and run with it, more power to them. (since my disability makes it hard to get to the store.)