I've been looking for the same thing, and the only option I found was something by Mad Katz or Intec or some other third party that could hold 40 discs, but the holder was all plastic from what I could tell, so I didn't feel safe holding them in that.
In the end, when Circuit City clearanced out the 12 disc cases for $4 a week ago, I bought all I could find. Now I've got like 6 cases all full, and only one extra. I figure the next time I need more, I'll go back to CC and pick up a few when they go on sale again.
Anyway, I've scoured eBay, different office stores, online media stores, and every other outlet, and found absolutely nothing (have been looking for several months). The closest option that I thought was viable was something I found at Officedepot, which was a "media wallet" designed for old 3.5" diskettes. One of those diskettes is a bit larger than a GC mini dvd disc, so they could fit in there pretty easily. I want to say it held 20-30, but because diskettes are a bit larger, I was worried the mini dvds would slide around and fall out.
I'm astounded that someone hasn't addressed this issue yet on the market, because I'd be buying it instantly.
