This is a second edition of the classic text by Katz. You may notice that I am the second author on this edition. Rest assured that all proceedings I receive from sales of this textbook at the University of Washington will go to the James Hewitt Scholarship Fund in the department.
You can find the book at Amazon.com, the UW bookstore, and many other places. There is also a resource page that includes errata (please send me any additions to this list).
The text is available from the bookstore as well as online booksellers. Unfortunately, there is not much of a discount/used market for this new edition.