Check out LexJet, we order all of our fine art medias from them.
They aren't wholesale but they started off specializing in aqueous print media and they have a ton of experience and a huge product offering including name brands and their own house brand (which just like most other materials is the same as the name brand, just sold under a different name for cheaper).
TBH I would just call them so that you can speak to a rep with experience instead of wading through their website...