Orbit is celebrating 10 years in the US with a number of books on sale for $2.99
While this is a US (and Canada) sale, some of these also seem to be discounted in other countries.
Available in most stores, amazon links below
Leviathan Wakes (The Expanse Book 1) by James S. A. Corey
https://www.amazon.com/gp/product/B0047Y171G
Ancillary Justice (Imperial Radch Book 1) by Ann Leckie
https://www.amazon.com/gp/product/B00BAXFDLM
Blood of Elves (The Witcher Book 1) by Andrzej Sapkowski
https://www.amazon.com/gp/product/B00276HAEY
Red Country by Joe Abercrombie
https://www.amazon.com/gp/product/B0076DEJMO
The Girl With All the Gifts by M. R. Carey
https://www.amazon.com/gp/product/B00CO7FLFG/
Soulless (Parasol Protectorate Series Book 1) by Gail Carriger
https://www.amazon.com/gp/product/B002NPCJ3G/
The Fifth Season (The Broken Earth Book 1) by N. K. Jemisin
https://www.amazon.com/gp/product/B00H25FCSQ
The Way of Shadows (Night Angel Book 1) by Brent Weeks
https://www.amazon.com/gp/product/B001E0V112
Feed (Newsflesh Book 1) by Mira Grant
https://www.amazon.com/gp/product/B003GFIVSE
2312 by Kim Stanley Robinson
https://www.amazon.com/gp/product/B004RD8544