I was walking through the library stacks, and I came upon a student who was looking for a copy of Shakespeare’s play, the Taming of the Shrew, which the student needed for a textbook. Our library has several copies of this play. We also have it on DVD & audio. (see Shakespeare Every Which Way from January of 2012).
Additionally, it may be useful for students to know about Project Gutenberg, which provides free ebooks for books older than 1924. Here’s a link to Taming of the Shrew: http://www.gutenberg.org/ebooks/1107.
Of course, you must be careful of the version your professor requires, but this could be a handy way to find free books.