I buy rolls of heat shrink in bulk. Several different sizes, for my own installs. I can cut it off and sell  by the foot for your installs. Please take a look at my selection and let me know how many feet you need.
 
The quantity of feet will be cut off in one continous cut and not individual feet.

This heat shrink is 1/2"  2:1 ratio and comes in black color.  
 
This 1/2" heat shrink (13mm) works on the following wire sizes:

4 AWG
6 AWG