In the first half of the 1900's, there were "race films" from Black-owned studios that were actually financed like this. The studio would create a trailer that they'd then show to theater-owners. Exhibitors who liked the trailer would pay an advance against the box office, and if enough signed on, the film would get made and distributed to them. Kind of like authors getting an advance on a book they're writing.

Do any of them (films or trailers) survive? I've never heard of black-owned studios and I'd like to know more.

Some do, but not many. Wikipedia has a good entry for “race film”, and http://dhbasecamp.humanities.ucla.edu/afamfilm/ looks like a great resource. Also check out https://www.criterion.com/current/posts/6845-black-cinema-at... and https://www.bfi.org.uk/news-opinion/news-bfi/features/short-... and other Google hits on “black cinema”.

Thanks, I appreciate the links.

video games have worked this way for a while, especially since the focus on mega-budget blockbusters. Some Kickstarter media projects also reflect this: someone makes a small short to fundraise, then commits to make a "fuller" length version based on the funds raised, linking the planned scope with available resources - sounds a lot like an agile software project!