I've often done fund raisers and "gatherings" at church and they charge whatever they wish (our pastor basically gives it all away) and I donate the meat and time. But, that's just me!
However, I always run the numbers to make sure they ask for enough to cover the actual cost (even if donated) so that everyone understands "free" isn't "free"!! 3x cost is a good ball park guest0imate.
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