I can completely relate to your situation. As a restaurant owner, we always have customers ask why an item cost more here than at the place down the street, and I have to explain that they are not comparing two equal products. Plain and simple, we are using higher quality products and we prepare our items from scratch by real people, so there are more costs to cover. It is hard to get customers to understand this. People tend to forget they are paying for the service aspect of things too. The money they are saving is being cut out somewhere, and it won't take long for people to see it. Remember that the individual booking these events rarely has the people eating the food in mind when they go with the lowest bidder. When there is a lower turnout at their next event and they can't figure out why, they will wish they had spent the extra money. There is no shame in charging a customer what the product is worth. I have never seen a successful business claiming "Cheapest food in town". Do what you know is right. Good luck.
I'd buy that for a dollar!
Lang 60 Deluxe w/ Chargrill
Custom Carolina Grills 3x5 Offset
Southern Pride SC-200
Traeger Lil' Texas Elite