Some options for purchasing the book:

   1. On paper (e.g. from Campus bookstore: new or used; new or used (very cheap!))
   2. Electronically, either from
       a. CourseSmart
       b. Wiley E-book

The electronic versions have nice reading applications, with good display options, and the ability to search the text, and to insert highlights and notes in your copy. It seems most suitable if you have a notebook computer. CourseSmart is a little less expensive, and has the advantage that you can choose either an online version or a downloaded version of the book. However it has the disadvantage that you don't keep the book: it expires after 180 days. Once you buy the book from Wiley, it's yours to keep. Also, that lets you download the book to two computers rather than just one.