Yup after freshman year I stopped buying books. For the rare occasion that I did need it, the library actually carries them in stock but no one ever uses the library for books anymore lol.
Seriously, does no one know this? And if the library doesn't have it you just go to the professor and have him add it, the library will get it in within a couple days.
You can do that if a used book is available for purchase. I've looked for used books in the past with no luck.
The problem is they change the material in the text books so you need to buy it new.
Also, most students don't want to be seen with a used book. They want to look fresh. New clothes, new iPhone, new books, and a hot car.
Well students should stop f^&*ing worrying about how new the book is and focus on kicking ass in grades.
Further, the material that changes in text books is the problem sections, not the actual content, because the material covered in undergrad courses is not changing - basic calculus has been pretty fixed for a couple centuries. There's not much changing about intro chemistry, or physics.
So, if you feel the need to have a book to study from, get the used one, especially one revision out of date (which is cheap as hell because all your idiot peers are buying the new one like good little sheep) this is perfectly good for reading and getting concept understanding. Then just go to the library and photocopy(smartphone picture) the problem section to do the homework.
I paid less than $100/quarter on books (and that was 7 years ago, not particularly different than today) got good study habits by spending regular time in the library, and kicked ass on the grades because of it.