I'm going to suggest it again, and let the chips fall where they may: Replacing student revenue with advertising or patronage revenue might be the answer.
It is probably not a good idea to simply allow ad money to select which books are used, so it would likely be an involved process of:
- Previewing texts by teachers,
- Selecting texts to use,
- THEN selling ad/patron/grant space for revenue.
Strict rules of the type and format of ads would also have to be applied.
Go ahead and say it: No one likes ads.
But who likes paying $500 a year for textbooks?