I'm no expert in this area but I did find a quite interesting blog post from Jim Kasson Photography:
In 1957...Kodak Tri-X...
Twenty exposures were 85 cents, and a 36 exposure roll was $1.15.
And that roll of Tri-X, the one that sold for $1.15 in 1957, or $8.43 in today’s dollars? You can still buy one. It’s changed a bit; it’s twice as fast and has finer grain, but you can no longer reload the cartridges. It’ll cost you $3.93 at Calumet.
The blog post was written in 2007. A quick check at B&H Photo shows a single roll of Kodak Tri-X 36exp ISO 400 selling for $4.99 today.
The Consumer Price Index inflation calculator shows that $1.15 in 1957 dollars has the same buying power as $9.74 in 2014.
Assuming that Jim remembers very accurately what he paid, I would say that a roll is about half of the cost today as it was in 1957. I'm too young to know anything about the 50's and I'm also no economics expert.
Film development gets considerably more complicated. The reason is that at one time the cost of the film included processing, and at others you had to process it at home yourself in a dark room, and obviously today you have a few options too with variable pricing.