Anglers Workshop has a really wide selection of blanks including fly rod blanks. Can't remember what they have in glass, but they seem to carry more brands and more selection than anybody. I just got a PacBay Quickline blank in 6 wt. Haven't started building it yet.
As Jim said above: proofflyfishing offers complete rodbuilding kits for glass rods. Also flyrodcrafters also offers complete glass rod building kits. The kits from both of these companies are inexpensive, but decent quality.