A.V.
You might still want to get the bags for the parents at the school so that every time they use the bag they advertise the school.
I'm not sure what the big schools do. If you don't have time for printed materials, is there anything that could be made? Do you know anyone who could design a cool logo that could be ironed on by staff? What about Oriental Trading? Go to their site and type in "Personalize". Or http://www.personalizationmall.com. Not as cheap as your $1 bags, but they usually have a fast turnaround. You could also make cupcakes and get toothpicks and either get school stickers or use labels to make double-sided toppers for them.