In the United States, one in five students does not buy all the required texts. And more and more, like Mr. Sarkis and Mr. Kinsley, are willing to go to great lengths for a cheaper alternative. "I got mad when I found out that our labor economics book was something like $90," said Mr. Kinsley, who, like Mr. Sarkis, graduated in 2001. "I didn't think I would read $90 worth in it, so I was determined to find something cheaper, and I spent five hours searching on the Web.