A few books in the Libertus (Roman Britain) series by Rosemary Rowe have dropped in price recently.
Death at Pompeia's Wedding, #10, is $1.99 at Kindle US
Kindle US:
https://www.amazon.com/dp/B004ZGLDWE
Kindle US/Smile:
https://smile.amazon.com/dp/B004ZGLDWE
A Whispering of Spies, #13, is £2.84 at Kindle UK
Kindle UK:
https://www.amazon.co.uk/dp/B00AMQFD0Y
Kindle UK/Smile:
https://smile.amazon.co.uk/dp/B00AMQFD0Y
Dark Omens, #14, is also £2.84 at Kindle UK
Kindle UK:
https://www.amazon.co.uk/dp/B00FYTGY5C
Kindle UK/Smile:
https://smile.amazon.co.uk/dp/B00FYTGY5C