Book 17 for me was an e-book. At the center of the e-book is the short story/novella "Hunting Monsters" which you can all read for free, right now, right
here. You should do this, because it's terrific!
At the bottom of the story is a link to buy the e-book for $.99 (cheaper than Amazon, and no DRM!). In addition to the story, the e-book also includes an interview with the author and an essay about some of her inspirations for the story.
The story itself is amazing, and I do recommend you shell out the $.99 to support the author and to see the context pieces in the e-book which I thought were really interesting.
See my full review
here!