Developing Drivers with the Windows® Driver Foundation, i.e. the WDF book, is apparently out of print

Looks like the going price on Amazon is >$250 :(. The good news is that you can still get the book as an e-book at O'Reilly, http://oreilly.com/catalog/9780735623743/, or at Safari, for around $50. Not as convenient as a hard copy IMHO, but it is better than nothing or spending $250.