Stasia Kehoe has an illuminating post on the subject of fees authors and illustrators charge schools for their visits. Here’s an excerpt:
Almost all authors do charge for school and library visits, generally in the form of a daily honorarium plus travel and expenses (I recommend stipulating something like “up to 3 (or 4) presentations per day”). EXCEPTIONS: (1) If the publisher is paying for your travel and hotel for a book tour or other promotional event, standard protocol is to waive fees for any schools you visit in conjunction with a publisher-funded trip. (2) If you have reached out to a school or library (instead of them contacting you) because you will be in their area, it is typical to charge a reduced, flat fee and no travel expenses.