Leviathan Wakes (The Expanse Book 1) by James S. A. Corey is $3.99 as a Kindle Daily Deal. It's sci-fi and I mention it because I finally got back to the series last week and read the third book Abaddon's Gate which I bought in 2013 when it came out and then forgot about it. Well it is absolutely great, one of the most exciting books I've read, and so I thought I would mention the first book as if anyone is left who doesn't already have it.
https://www.amazon.com/dp/B0047Y171G