I don't find the price of film that expensive. For me my hobby is very affordable. As the former owner of a small business, I would also like to add the cost of maintaining an inventory is also a significant cost, as is things like insurance, etc. It's called overhead. Personally, I'm surprised that we can buy film as cheaply as we do.
When I was partnering with my father in law in his lawn care business, I sat down and calculated the cost just for the mowing side of our lawn care business. Factoring in everything, it cost $50 just to pull the truck up to the curb. That was before the crew got out of the truck, started the mowers, etc. This was back in 2000. Not realizing the total cost, we were charging $50 to mow (acre size lots), and we were losing money fast.