They were free - but only for a few hours last night (UK time) as I noted on my thread.
https://www.mobileread.com/forums/showthread.php?t=67412
There are a couple of new ones today though:
Dark Pursuit (Kindle Edition)
http://www.amazon.com/Dark-Pursuit-e...=discounter-20
Exposure: A Novel (Kindle Edition)
http://www.amazon.com/Exposure-A-Nov...=discounter-20