We had a prof who said he only used to book for the problems and they changed their order each edition. He would give us the previous years question numbers so we could buy the book used.

My friends and I ended up splitting a single copy of the book and texting each other the homework questions each week.

I had another prof who used an open source book and only charged us the price to print it. You could access it for free in PDF online, or even the source to generate the book in additional formats.