You may know some of this, but I suppose it's worth repeating now and again. ;-)
Choc_Addic mentions Temco. They are a manufacturer, under license from Sandvik, to make genuine Kanthal wire. Always buy genuine Kanthal wire from US vendors... the China stuff is pretty inconsistent, and sometimes just plain crap.
As to on-line vendors, simply Google what you want and see what vendors pop up. "#500 stainless mesh" for example... and you get
MeshWizard.com.
Most of us tend to buy attys, mods and supplies from 3-4 to as many as 15-20 different vendors, depending on their inventories and best pricing.
Fasttech is OK if you need a low price... if you don't mind the wait from China, and slow return issues. There are several vendors that price very close to Fasttech these days, with 2-4 day delivery, instead of 3-4 week delivery.
When buying clones, do your research... some are much better quality than others.