Various in the first in series sale on Amazon.co.uk:
Charles Stross:
The Atrocity Archives (THe Laundry Files 1) at £1.49
https://www.amazon.co.uk/Atrocity-Ar...5175074&sr=1-9
Steven Erikson
Gardens of the Moon (Malazan Book of the Fallen 1) at £1.99
https://www.amazon.co.uk/Gardens-Moo...5175074&sr=1-4
Hugh Howey
Wool (Wool Trilogy 1) at £1.99
https://www.amazon.co.uk/Wool-Trilog...175165&sr=1-14
Terry Pratchett & Stephen Baxter
The Long Earth £1.99
https://www.amazon.co.uk/Long-Earth-...175259&sr=1-33
Bernard Cornwell
Harlequin (The Grail Quest 1) at £1.49
https://www.amazon.co.uk/Harlequin-G...175165&sr=1-16 (cross-posted to the Historical thread)