You'll be fine.
You'll have roughly $4 per person in costs: two meats, three sides, and consumables.
I've charged anywhere from $8-14 on this type of gig. If you are paying servers (I've always found volunteers or "volunteer" my sons and pay them with food!) you'll only need them for an hour or so.
Southern Brethren BBQ Competition Team
"It's all about getting paid!" - Myron Mixon
"I love being hated in my hometown!" - David Hair
KingFisher Gator Rotisserie cooker, WSM, Stainless 5 burner with IR gas grill, Turkey Fryer, Weber JD Commemorative grill, slightly used Bandera chamber for future use as a cold smoker, Masterbuilt 40" insulated ELECTRIC smoker