Affordable catering for birthday party

We're hosting a birthday party for my young daughter in June (Inflatable water slide, baby pool etc) and I'm looking for some affordable, yummy food for our crowd that will include about 20 kids and their parents. i'll have a lot of family in town and won't have a ton of time to prepare food myself so I'm seeking ideas for catering--open to all types of food as long as it includes a few vegetarian options for those who don't eat meat. Any ideas? Food trucks seem too pricey. Thank you!