What is the cheapest way to buy relatively good-quality textbooks (Amazon, University of Toronto Bookstore, etc.)?
Amazon usually has pretty decent deals for used textbooks but I think it is always prudent to check other sites like tusbe.com or officail UofT facebook groups for buying and selling textbooks. Another option is e-books, so if you are comfortable doing readings, practise sets, etc. from a screen as opposed to a paper book, then that could save you some money too.
I also wouldn’t buy the textbooks just yet since some courses do not actually require the textbook, it would be best to go to the first lecture and hear what the professor has to say about the textbook. This way, if you decide you want to take another course or the textbook is not required, you don’t lose money on buying a textbook.