If you are looking more for protection than for
easy access, try an otterbox, which is a tough,
waterproof, crush resistant box.

I find that the otterbox 2000 fits a lot of personal
electronics often with extra space for other items.

To make the case belt mountable, pick up a
3 magazine pouch for an M-16 at your local
surplus store. Cut out the dividers, and
you will find that it fits the otterbox quite well.