The most comprehensive resource for bookmaking supplies that I've stumbled across so far is New York-based Talas. Established in 1962 by Elaine and Herbert Haas, this conservation, preservation and restoration company offers an extensive line of bookmaking, archival storage, fine-art printing and framing supplies for bookmakers and photographers, as well as products for librarians and preservationists.
In the bookmaking category, you'll find bookbinding tools; presses, sewing frames and equipment; book cloth, boards and decorative papers; and adhesives, threads, tapes and headbands. For photographers, there are portfolio cases, archival storage supplies, fine art inkjet papers and framing supplies. You can shop online or download a PDF of the full catalog.