If you have a child going to college in the fall and want to save as much as possible on texbooks I recommend internet shopping.  It's important to have the ISBN number and edition in order to get the correct book.  Two of our daughters are through college and the third one starts in August.  Buying used books is the way to go and sometimes the college textbook office has good deals.  It's important to get the book list as early as possible.  However, if the class is using a new edition you won't be able to find as good a deal, but some internet searching may give you a little discount.  The sites I recommend are http://www.betterworldbooks.com/ and http://www.bigwords.com/.  Better World Books helps fund literarcy projects so I try to use them as much as possible.  Good luck to you and your child.

That is a great idea to post this information!  In law school I also utilized half.com, ebay and Craigslist.  You can get your books much cheaper than at the bookstore.  I also sold my textbooks on these sites as well. 

Some people don't like to buy used books thinking they are missing out on their education if they do.  I honestly noticed no difference and many times got "like new" books for nearly half the price. 

Amazon.com and BarnesAndNoble.com also sell used text books - sometimes they have the best prices.

Something else to think of:  for some books, the edition is not nearly as important as others.  For science text books that are updated with new information for each reprint it can be vital to get the right edition; for English it may not be, as long as the same selections are in both editions - I used my father's annotated copy of Shakespeare for a class I took in college instead of the edition the professor had the bookstore - no cost to me, all the act and scene numbers were the same, and I had my father's notes as well as the annotations.  For any class you can, check with the professor - I did, and was able to buy older editions for some classes at a much lower price, because the differences were neglible - but be careful to listen to the professor; some care immensely and some couldn't care less as long as you have the right content.