Here's is where I used to get sleeving back when I modded computers:
http://www.crazypc.com/products/case...le_sleeves.htm
And heatshrink to go with it (keeps the ends from fraying):
http://www.crazypc.com/products/heat_shrink.html
But honestly, the sleeving has lots of little holes for dirt to get in, and it's a PITA to clean. Good for shelf queen, but not for actual use IMO...