Make your own film developer? You can use coffee to do that.
20170815/https://en.wikipedia.org/wiki/Alternative_process
20170815/https://en.wikipedia.org/wiki/Caffenol
20170815/https://people.rit.edu/andpph/text-coffee.html
20170815/DuckDuckGo home made photographic film and developing
20170815/DuckDuckGo home made photographic film
20170815/http://makezine.com/2008/05/14/make-your-own-photographi/
20170815/http://www.flickr.com/photos/dark_orange/sets/72157603226919391/
20170815/DuckDuckGo homemade photographic film
20170815/http://photography.wikia.com/wiki/Chemicals
So, although home-made film developer is promising, home-made film is a bit more difficult. Coating the film with the photosensitive material is a bit more complicated, and getting the photosensitive material? You might have to buy that specially.
So in other words, the most expensive material in traditional photography is the photosensitive material. Finding a way to make that material cheaper will make all of traditional photography suddenly magically cheap.
Other, less promising sources.
20170815/https://en.wikipedia.org/wiki/Gum_bichromate
20170815/https://en.wikipedia.org/wiki/Carbon_print
20170815/https://en.wikipedia.org/wiki/Collodion_process