I searched Walgreens and CVS for the diabetic case, with no luck. But I bought a locking cash drawer at the same time, which has been working out pretty well for holding all my junk. I store pre-filled ADV tanks in one spot, charged batteries in another, spent tanks in another, bottles and spares underneath, and so forth. If you're into organization, I recommend it. (A tackle box might work too).
I've been using a shirt pocket, but the problem is I keep running out of clean shirts with pockets. The eyeglass cases are too big. After reading this thread, I just strapped on a mag light holster. It's a good size but offers minimal protection against bending and snagging. But I'll try it for a while. What I envision is a leather knife pouch with a fold over top and a magnetic snap.