Setting outrageous prices for textbooks is a practice of publishers, but in few cases does the economics seem to justify it. As Wang and Wang argue, learning efficacy could be the way forward for OER to reach the mainstream. Their research demonstrates that the quality of learning outcomes for OER matches that of commercial textbooks, and when measured using rubrics like quality of peer-based discussions, OER even outperforms.
https://www.moodlenews.com/2017/the-business-of-making-oer-a-standard-for-affordable-textbooks/