I am the yearbook adviser at my school. We went up to $40 prepaid price this year from $35 because we are having an all color book for the first time. We produce a 160 page book that covers PK-12. We have about 850 students in our district.
From what I've heard interacting with other advisers, we are a fairly low priced book. I hear prices in the $70-$90 range most frequently. I think most people have no idea how much money it takes to produce a yearbook. Our book, which we purposely keep small and as no-frills as possible, costs about $20,000 a year to produce. We make about half that in ad sales, but the rest has to come from book sales.