Bargain shopping for college

I spent the summer watching my niece and almost-son prepare to go to college.  The last of the two, my niece leaves in the morning.  As I have a child starting college in the fall, and another the next year, I am very interested in the process of gearing up to go to college.  It just looks plain expensive.  


Being the consummate planner, I have purchased two trunks and have began to put things aside for my son.  This way, I can purchase items he will need on clearance, and pay less than what I am watching others pay.  I am excited about the prospect of having an excuse to budget shop for the next two year.  


The subject of textbooks is a bit scary to me though.  First, the amount of time you have to shop for college books is severely limited. You don't get your textbook list until a week or two before school at most.  Second, there are no clearance sales to help you stockpile textbooks.


My friend did have some success at getting textbooks for less than half price from Amazon.com.  There were ebook options and used book options.  The only problem was shipping time for the books in print.  If you have a source for a great textbook option, please drop a note.