A couple of titles in Georges Simenon's Maigret series have dropped to £1.99 at Kindle UK, both towards the end of the series. I'm traveling again, so bare-bones posts...
Maigret's Anger, apa
Maigret Loses his Temper:
https://www.amazon.co.uk/dp/B07D4764QQ
Maigret and the Nahour Case:
https://www.amazon.co.uk/dp/B07GRC3M66