PDFs are good for the odd reference here and there, but it's really tough to study off those for exams etc.
Mass photocopying works. One guy wold get hold of the book, go to a photocopier who does it for cheap, and all of us would get a copy and pay him later.
Or do you have book banks there? A lot of people in college used those here.
Back in college I used a combination of high quality pirated books, photocopies and borrowing from the library. If the book was really important and good, I'd get the actual book (price was nowhere near that high as you mentioned though).
Didnt like book banks too much cause you had to return all the books at the end of the semester, ideally want to keep some of them for reference later on.