I was under the impression Comp One did not sell to retail customers. I think all the local yards buy or have bought from the local branch, but I can't think of any DIYer who has mentioned them. I'd love to be proven wrong.
Depending on where the OP is located, Fiberglass Supply in Burlington WA carries almost everything including warp UD S-Glass and carbon. Best E-Glass prices I've seen posted as well.
I picked up some foamcore from them last year, with no problems.
I think what you need to do is not call them up and start asking a lot of questions.
Make it sound like you know what you need and you should be ok.
also try http://thayercraft.com/