was thinking about this further and I forgot 2 details. If the meal went over the amount the parent pays and the other perk for the teacher is that they get a free meal.
We asked the more popular teachers in our school and said "Would you go to dinner/lunch with one child(winning bidder)and thier parent at xyz restaurant?" Then at the Silent Auction it is a package deal, the teacher and the restaurant. Some teachers did not like certain restaurants and we also took into consideration where the teachers lived and suggested restaurants close to their homes. But we had to work with whatever donation we had.
I tell you, most dollar amounts to restaurants were $50 and most bid up to $75 and some higher. But this type item was good for 2 reasons, getting more money than the actual donation amount(rare) and getting the teachers involved. We had more teachers offer to go than we had certificates.
If a gift card goes toward an outing with a teacher, is a specific teacher named, or does a parent bid for their child with whatever teacher they want.
At our school, the teachers all pay for their own things. They do not have to be very expensive--a picnic at the park or a movie or something like that...
You can't "force" a teacher to participate, of course, but our principal strongly encourages it because it usually brings in big money, especially in the younger grades.