Source for Shrink Tubing?

I terminated several pairs of speaker cables with banana connectors and want to add shrink tubing at the union of the connectors and cable.  I am looking for 3:1 shrink tubing in both black and red in 1/2" diameter.  I figure 3' of it would meet my needs.  I found a few sellers on-line, but either they require a minimum dollar purchase or the smallest quantity they offer is far more than my need.  Can somebody recommend a source for such a small quantity?   Thanks very much.  
Parts Express would be my choice. However, it's only 45 minutes from my house, so I just stop in occasionally. But shipping is only $6.95, so you can't go too far wrong.
I'd check locally in one of your electronic parts shops I buy any I need form my local shops they just cut it off a roll.  
I realize that the OP found what he needed, but in case this helps anyone else ...

A few months ago, I replenished my inventory of 3:1 adhesive backed heat shrink from the folks below.

I ordered quite a bit, but I believe their minimum quantity is consistent with your needs (i.e. 3 feet of red and 3 feet of black), and priced far better for a specialty item like this than most outlets (3:1 is not that readily available).

They delivered exactly as advertised:

Thom @ Galibier Design