I tended away from asking for money and looked instead for material donations to offset what would otherwise be incurred costs. Asking for money for catering is difficult... trading advertising time/ posters at the screening for supporters etc... for actual foodstuffs is relatively easy. They get positive local advertising to a relatively affluent local crowd who supports businesses who support local artists.
This is very good idea. You gotta get in there fast, mind you.
I operated a series of delivery joints in about a dozen various collegetowns, many years back. Every organisation on campus would be hitting me up for "food donations" at the start of the college year - sad story is; the start of the college year was already too late.
Every campus radio-station, theatre group, heck - any ongoing concern of any type - they've already tapped many of the local businesses well before the college year starts. There's only so much that local businesses can agree to give away in advance. Most of this happened at the end of the previous year.
Still, it's worth asking for. The worst they can do is say "no".
Some tips:
1) Go talk in person. Much harder for a manager to tell you to go pound sand, if you're standing in front of them. It's very easy to, over the phone.
2) Talk to the daytime managers. Night-time can get ridiculously busy. (Drunk/stoned college kids ordering late-night food? Say it ain't so!)
3) Even if you're too late to arrange a dedicated commitment for free food, you'll still be able to work out some kind of significant discount - if you have a schedule planned, and appear to be organised.
4) If you happen to suck at asking strangers for free stuff, send (or bring with you) someone who's good at it. Consider this part of the "delegation" aspect of filmmaking.
In short, local businesses
do want to get involved with local college productions & enterprises. You just gotta be in there, before the rest of the pack, to get the most out of it.
Of course, this doesn't directly answer the original Q of "how to get funding"... but, as mentioned, the more resources you have freely available... the less actual dollars you need.