Showing movies---either not-yet-released films or classics---is an ideal way to raise money. People love going to the movies, and you can make the event casual or as swanky as you want.
The costs of renting a theater can vary depending on the theater, but depending on how fancy you are, you can charge anywhere between $10 and $50 a ticket. Potential ticket income ranges from $1,000 to $25,000, according to Hollywood Fundraiser.
Showing a not-yet-released film may be difficult if it was made by any of the major film studios, but oftentimes, independent filmmakers are looking for a venue to screen their film in front of a large audience.
There are companies out there that work with producers to get independent films screened. One of these companies is Hollywood Fundraiser. The company notes on its website that most films are available for only a short period of time, so deciding a date (and sticking to it) is of the utmost importance.
One of the great things about a movie screening fundraiser is that there are seldom any "limits to the expandability, number of screenings and profit potential," according to Hollywood Fundraiser. Money will be made on ticket sales, but there are other avenues for bringing in the bucks as well.
Sponsor advertising (e.g. commercials, graphics) shown before the screening is another source of income. Another option would be to auction off memorabilia at the event.
Make sure you are working with a legitimate company when it comes to securing the rights to screen a movie. The legal issues that could arise could cost a lot more than what you made at the event.