Hello there! :)
A new semester is about to start really soon! Have you got your copy of textbook?
Before making a purchase, you should check with your professor if:
1. You can use an older edition (because it is usually cheaper)
2. You really have to buy the textbook (because some textbooks are compulsory, some are not; because some textbooks are on the reserve in the library, and you can certainly make use of it)
Before buying that textbook, compare the prices from your university bookstore with other online sellers.
Great sites to get textbooks:
You need to sign up for the Amazon Prime (http://www.amazon.com/b/ref=lp_student/?node=668781011) because it's free, it gives you free two-day shipping, and it's for a year.
*** Always check for the shipping rate and the shipping date. Some books from used-book sellers take 1-2 weeks to reach you.***
Of course, you can choose to rent your textbooks, get used ones from your friends, or buy the kindle version. At the end of the semester, you can choose to sell back your copy to the university bookstore, other bookstores, or Amazon. If your friend wants it, that's even better! (saves shipping fee) Anyway, the university bookstore and nearby bookstores pay pretty low for the textbooks. You should check with a few buyers before you sell it off.