Check www.poolndarts.com They have hard cases for balls, and then there's an aluminum case for the balls and your cuestick.
Scott Lee
http://poolknowledge.com
From Castillo Leather: http://castilloleathergoods.com/?cat=9
I have one, these are very nice!
CUE BALL CASE……..
Description: Leather Cue Ball Case with keychain type hook so it easily attaches to your cue case.
These come in very handy if you carry your own cue ball for league play or if you’re at a Pro event and want to store your cue ball while collecting autographs.