Elann.com offers one of our favorite base yarns — a soft, natural white, 100% Australian, 26.8 micron mercerized wool. It's available in several weights at a very afforable price and it comes in gorgeous colors, too!
Knit Picks offers Bare yarns in a range of natural fibers and weights and gives a 15% discount on bulk orders.
PRO Chemical & Dye offers a wide selection of dyes and other textile craft supplies, excellent technical support and visiting artist workshops.
Wool2Dye4 manufactures, distributes, and sells quality undyed yarns.