An omnibus of four titles in the Maigret series by Georges Simenon has dropped to £5.99 at Kindle UK, which is a nice price if you don't have any of them. Several have been on sale individually in the past, though, so check carefully before you buy. Also, keep in mind that some (many?) Maigret titles have different names in different countries or have been republished with different names at different times.
Titles in the omnibus are listed in the blurb, and keeping the "different title" thing in mind, it's nice that they tell you a bit about each one.
link:
https://www.amazon.co.uk/dp/B00ZGZDAW4