There is another alternative and that is to buy a used previous edition. I did this for all but one of my nursing classes, never paid more than $25 for a book and often found the text for less than the cost to ship it (less than 5 bucks). For the most part, there is very little difference in content between the editions and publishers ought to be ashamed of how they rip students off. But I digress.
There is some risk in this, since your syllabus will usually not match the text. Many times, the syllabus will have the name of the chapter or a description of the assigned section, in which case there's not much of a problem. In the cases where only the chapter/page was listed, I would ask the instructor for the title/section information. In the very rare cases (I only had one) where a professor absolutely insisted that the current edition was needed, I simply asked a fellow student who had the new text if I could borrow it for a few minutes and wrote down the chapter headings to cross-reference to my text.
YMMV, but I spent less than about $350 total for my nursing texts, right through to my BSN.
I bought most of my textbooks from Chegg or Amazon. Amazon allows you to rent a book for a semester (which may be a little tricky for some students who attend schools that are not on the traditional 2 semester system, like my school). If necessary though, you can extend the rental period. Chegg is another great rental site as well. Affordable prices on both sites. I recommend both I ended up purchasing 95% of my books while in school, but I bought the really cheap versions(like the ones in "fair" condition, heck I don't care if the book is little banged up!) .
I will suggest half.com, eBay, or amazon. I prefer eBay coz I will see the exact picture of what I am buying and not a stock photo or tell the seller to send me the actual picture of the item I will be receiving. I purchase textbooks in a like new or very good condition on eBay since there will be no highlights, ripped pages or sorts on them so as to get a good value for my money.
The best part of it is that I sell them on eBay after the end of the class for virtually the same price I got them or more. I have never ran at a loss on the original price of purchasing these books so far.
I also do not rent textbooks because I can not get my money back afterwards.
I am not on financial aid so this is my own little way of saving while investing in my career.