How much would a 16mm film stock cost for 30 - 40 min
http://www.matthewwagenknecht.com/the-actual-costs-of-film/
“A good estimate for a 90 minute movie shot on Super 16 recans at a 4-1 ratio would be $5,625 for film stock if you pay $125 per roll. If you are willing to use short ends this cost would go down.”