Kagura, I would walk about campus the week before uni and look at all the bulletin/notice boards for cheap books. If all else fails I'd definately get my books of
Textbook Exchange - Welcome to Australia's largest second hand textbook site and only overnight.
You cannot borrow reference books from the library during the day. You can only borrow it 2-3 hours prior to the library closing i.e. after 6pmish.
If you are facing and financial difficulties please visit a UWS welfare officer in the first two weeks, where they could possibly offer you a $200 or so book voucher, if you can prove your extreme financial difficulty.