I agree with what's mentioned above, but also what's been my experience is if you don't buy the negotiated bundle at the college, you may be missing out on REQUIRED materials. For my 3 classes I had this semester:
Required Computer bundle- I could have bought the books separately at other websites, but I needed a code for Sam 2007 and just the code is about $40 I think? There was a "free" (ha) code included in the bundle. Without Sam 2007, I wouldn't be able to do some of my homework that had to be submitted online.
Chemistry- same deal. The bookstore bundle had a "free" again, lol- copy of Webassign. If I didn't buy their pack, I would have to pay full price for Webassign. I needed it to turn in homework! Also, I REALLY liked the study guide that came in the bundle. I at first thought it was a waste, but it walked you through the problems so it ended up being a valuable resource.
Math- sure, I could have gotten the book on
amazon or chegg, but what about MyMathLab? Luckily, my class doesn't require it, but some do. You'd have to pay retail to get a copy of that, if required.
I feel bad for those who thought they were saving by renting, and then had to piece together the rest of the stuff they needed later. I love how the college bookstore bundles seem to include everything you need for the semester. I know the initial price can make you go

, but it's been worth it in my case.