There are several good sources for buying textbooks online, but my favorite, because it is user friendly, is www.schoolsoup.com . Not only is it a great source for inexpensive books, but a good place to look for scholarships.
You should be able to save $60 to $70 a semester. Remember that books cost about the same as the class--they average from $75 to $150 a book. Science and math books are usually pretty pricey. In graduate school some of my books were about $200 each.
Every class requires a book and, in some cases, extra supplies and materials. That is part of getting an education. So, when you make a commitment to go to college, know that you need the necessary resources to buy your books.
Go to class prepared. Have your book on the first day of class. Be ready to take notes and complete your assignments on day one. Without a textbook you will be starting off on the "wrong foot". Do everything in your power to be a successful student. It is your responsibility to buy your books and supplies.
If you buy your books online, it takes a week to ten days to receive them and you do need to pay for shipping. Get the ISBN number of the book--it is located on the lower right corner on the back book cover. Be sure that you are buying the student copy and not the teacher's edition.
While you are waiting for your book to arrive, go to the college library. They have a copy of every book that is being used in the classes. You cannot check it out, but you can use it for a couple of hours. Once you are finished with the book, sell it back on school soup.