Recently we were contacted by two companies selling cloth, buckram, and imitation leather substantially below the prices asked by major binding supply houses.
They sell a variety of weights, colors, and widths and will sell small amounts.
They say prices can be kept low by not maintaining a perfectly complete stock, by not issuing catalogs, and by not using salesmen.
They sell by phone and mail. Send a swatch of what you want, and they'll supply it if available. They are:
Steiner-Liff Sales Co.