Depending on what the community service project is like, perhaps there’s a chance to tell businesses that they will be “sponsors” of the program by showing their support via donations. And then you can go on and define what sponsorship means—platinum, gold, silver, honorary etc. etc. And then attach a $ figure to each level.
If you’re not necessarily looking for $ but also for food / services, mention that businesses can reach different sponsorship by providing equivalent services or gift certificates etc. etc.
Some tips I’ve picked up at trying to get local businesses to help out my school organization.
Also—don’t fear. Local businesses love getting involved with the community, and it’s important to build a good relationship with them that can be advantageous to both parties in the long term. And sometimes, it might be harder to get businesses to donate money, but food / services / discounts are more easily providable. Also, even asking if they’re willing to put a donation box for any customers wanting to donate to your cause would probably go over well.