Hachette Book Group has a number of mysteries (via several of their imprints) for $0.99 right now…
Murder by the Minster by Helen Cox, Kitt Hartley #1
Kindle US: https://www.amazon.com/dp/B07RDJTPQY/
Kobo US: https://www.kobo.com/us/en/ebook/murder-by-the-minster-1
Murder On Mustique by Anne Glenconner
Kindle US: https://www.amazon.com/dp/B08KQ2N7SB/
Kobo US: https://www.kobo.com/us/en/ebook/murder-on-mustique-2
Death from a Shetland Cliff, Shetland Sailing #8 (most recent, 2020), by Marsali Taylor
Kindle US: https://www.amazon.com/dp/B08BZ9RM7W/
Kobo US: https://www.kobo.com/us/en/ebook/death-from-a-shetland-cliff-1
Murder on the Edge, Libby Sarjeant (recent, 2020), by Lesley Cookman
Kindle US: https://www.amazon.com/dp/B08FHWL83P/
Kobo US: https://www.kobo.com/us/en/ebook/murder-on-the-edge-1
The Bone Garden, DI Wesley Peterson #5, by Kate Ellis
Kindle US: https://www.amazon.com/dp/B00GVFUW7O/
Kobo US: https://www.kobo.com/us/en/ebook/the-bone-garden-3
Thieves Dozen, Dortmunder short story collection, by Donald E. Westlake
Kindle US: https://www.amazon.com/dp/B001I3BQT2/
Kobo US: https://www.kobo.com/us/en/ebook/thieves-dozen
After Dark, My Sweet, by Jim Thompson
Kindle US: https://www.amazon.com/dp/B005IGVSFW/
Kobo US: https://www.kobo.com/us/en/ebook/after-dark-my-sweet
The Silver Collar, Thomas Hawkins #4, by Antonia Hodgson
Kindle US: https://www.amazon.com/dp/B08HYQ6SQ6/
Kobo US: https://www.kobo.com/us/en/ebook/the-silver-collar-4