Cog belt question?

I just bought a set of cog pulleys and now I need a belt. Where is the best place to buy a belt?

Also are there any tips to keeping the belt on and helping it last longer?

I get my gates belt from a local NAPA. Cogs dont need alot of tension to work properly, I have mine tightened at about 1/2"to 3/4" of play.

I found them at motionidustries.com. They have all the Gates belts. I tried Napa, but there computers were down.