Saving Money on Textbooks

I am pretty sure the textbook industry is extremely lucrative. Emphasis on the extreme part.

Here are my tips and tricks to help save you money:

Don't ever buy from the university bookstore. Like never, ever. Buy online! or from other students on campus.        
I'll never forget the time, my old roommate bought all of her biology books at the university bookstore. She broke the record for most monies spent at the store.

Email the professor. 
I usually email the professor way ahead of the class start time. I ask: 1) is there any other materials I need besides those listed online? 2) can I get away with the previous edition of the required text? The professor is most likely going to say something like this, "nope and nope. You need to buy the required text from the university bookstore" Then you ask from 3) syllabus. Sometimes you can preview the beginning of the book on websites. I compare say, the first edition with the second edition. If the chapters are similar and matches/comparable with the syllabus, I'll buy the cheaper edition.

Consider e-books. 
You can get Amazon Kindle software for your computer. Most universities/colleges allow laptops in the classroom. I have a wide screen monitor...so reading off a computer screen is somewhat comfortable/manageable.

There's really no such thing as free shipping. (It comes with a price). 
Better World Books just includes it the selling price. So you don't think your getting the best deal. Once in a while I'll order something from BWB just because they support carbon offsets and support literacy programs.

In what situations should I rent and/or buy? And when can I positively buy the older/cheap edition?
My general rules are as follows:

• if the publication dates are so close together. Like the first ed. was published in 2003, second edition published in 2005. I'll automatically choose the cheaper version.  It's a pretty safe bet that the company just changed 1 or 2 graphics and called it "new and improved". I'll compare buying (and the sell back price) vs renting. 
• if the book is published every single year, yet the publisher make significant changes to the book each and every year (take You Decide! series of books as an example)...I'll rent. Right now, you can sell your You Decide 2011 book on Amazon for $15. I bet when You Decide 2012 comes out, you won't be able to get top dollar for your book.