Consider Phlebas (a Culture Novel Book 1) by the great Ian M. Banks is $2.99 today. If you have any interest in sci-fi his Culture novels are a must, about a far future humanity that is post-everything and yet gets into the most interesting situations. The technology is mind-blowing and the social interactions are complex and like Alistair Reynolds' Revelation Space books cause all kinds of dilemmas exciting situations. This is thinking person's sfi-fi with exciting action on every page. The order of the 10 Culture novels isn't important but most start with this or Player Of Games.
Book 2 is dropping September 17 and book 3 will be out on December 10! This guy must write with both hands. Of course he has Christian Cameron helping out. I was just looking to see if the next book in Christian's great Sir William Gold series has a drop date yet and instead I discovered book 1 in his new series, titled The New Achilles. I had no idea he had started a new series. This guy is amazing. And his books are always reasonably priced. This new one is $9.99 and his William Gold books are all between $2.99 and $4.99. The Ill-Made Knight is the first in that series.