When I was in college, one of my instructors used these "clickers" that cost students $40 per semester to rent. They used radio to allow submitting realtime quiz answers during class.

iClicker.

F#$* those things.

Faculty at the two higher eds I worked as staff at hated the cost of books and student materials too, and tried their best to keep them down. Most of them. Publishers like Pearson and Cengage started doing things like discounting teacher's editions and/or including curriculum (slide decks, all level of evaluatons and more) in exchange for becoming the learning portal and getting their hands on that sweet, sweet PII and marketable data, not to mention the yearly rolling editions of their student texts with single-use portal key codes.

This free market correction sure is taking its time...