Snacks with some cakes and ice cream will do fine
Birthday Party Etiquette Question
My son's first birthday party was cake and ice cream only, because our finances were tight. On the invitations, I specifically put cake and ice cream party, so people knew not to come hungry. I think another idea for a cheap meal is corn dogs. Kids usually love them, and they tend to be filling and a lot less messy than hot dogs and / or chili dogs. Just my opinion. Also, if there is a Party City store in your area, they often have wonderful deals on little gift bags that the kids love, but don't cost much at all.
Good luck, and happy birthday to the 5 year old!!!