How about all pitching in on a yard/garage sale in the parking lot?

Some pet businesses might be happy to donate prizes for draws or raffles, in return for their sign being displayed somewhere (they'll provide the sign). Shelters and others might have information tables. SPAY AND NEUTER, you get the drift. Get the AC bylaw people out also, to educate!

I bet the media would help with free (almost!) publicity - people LOVE a big garage sale. OR little ones! I bet a lot of stuff could come from the students' parents.

Then have the cookies, hoodies, etc for sale. See about donated pizza or something.

I don't know much about your town, but this would be a great community event.