1. Talent (although assuming you write and direct yourself, and use unknown actors, this can be brought down to under a few thousand).
2. Film stock and processing (over 50k with celluloid, but obviously digital is much cheaper).
3. Equipment (camera, dollies, lights etc.): 40k
4. Crew: 70k for a 2 week shoot with a cheap crew, including catering
5. Post production: 40-60k
This sort of money will get you a surprisingly professional looking 90 minute film. However, production costs on film are always eclipsed by marketing costs. It can cost thousands of dollars just to market a film to the distributors, no matter to consumers.
Obviously, you can make a film for much less than this, but only if you want to make a film like Clerks or In The Company Of Men (i.e. one location, shot in a weekend).