The most we've paid is $1150 fee plus 50 sandwiches for volunteers. The fee would have been around $1500. It was a mistake and we won't pay anywhere near that again.
I actually prefer the 30% commission over a flat fee. I can price this into the food.
All the vendors will be paying the same fee or commission. So all the vendors should be pricing their offerings accordingly. I don't concern myself with explaining why the food is expensive. I keep the focus on value in all situations.