And eBook is ... well, free. A single copy might run you $40, as here: https://www.bookbaby.com/single-book-printing
Used/resale markets for existing texts are of course an option. And many photocopy shops can throw a usable binding on a text, though photocopy costa alone will be comparable to the price cited above, at $0.07 - $0.08 per page generally.
In many cases, ebooks become a very reasonable compromise.
Hasn't been my experience at all - in fact I haven't noticed a relationship between quality and price of textbooks in either direction.
> you spend so much time and effort seriously working through a math book that whatever money you paid for it looks like something that does not matter at all.
You'll spend the time if the book is good. That's an advantage of free books - you can discard the bad ones without wasting money.
Maybe gp was referring to cheaper “international editions” available for certain popular texts. I heard they intentionally add errors to the cheaper editions (or at least shuffle exercises to make students’ lives miserable if their instructors assign textbook problems).
On multiple occasions I've simply printed the PDF, gone to FedEx and had them bind it. Very cheap, including cost of paper, toner, etc.
A B/W laser printer is fairly cheap, if you don't have one. I was so glad once I bought one.