The Kindle version of John Jackson Miller's Star Wars: A New Dawn, the prequel to Star Wars Rebels is only $3.99 today! We are not sure how long this promotion will last.
A New Dawn is the new dawn of Star Wars publishing. A few months ago, LucasFilm announced that all the previous novels, and comics were going to be called "Star Wars Legends," and that moving forward the new material will be consider official canon.
A New Dawn was written by John Jackson Miller with input from Dave Filoni, Simon Kinberg, and Greg Weisman, the executive producers of Star Wars Rebels.