How many folks you thinking of having?
Food, especially with a grill to cook or smoke ingredients in advance on, can be a much smaller expense than you probably realize, so don't base your number on that. Especially if you don't do the traditional meat-off-the-grill, veggies & bread thing, but instead offer a selection of large snacks & hot appetizers, like a spanish Empanada bar. Everybody gets full, everybody gets a choice, and there isn't that artificial "sit-down, meal-time while the parents look on" vibe.