Given the amount of silver in a roll or sheet of film, I would think it's a small fraction of the cost of manufacture, distribution and retailing. The cost of all the other raw materials going into film increases as well, and I would think it increases faster the smaller the volume the manufacturers' purchases become. What once was a high-volume business has become a niche market, and the economies of scale aren't as substantial as in the past.

Buy it while you can. The cost will never come down.