Some random price drops in the US...
Murder at the FBI, Capital Crimes #6, by Margaret Truman, $1.99
Kindle US:
https://www.amazon.com/Murder-FBI-Ca...dp/B07H14FZBX/
Kobo US (discountable):
https://www.kobo.com/us/en/ebook/murder-at-the-fbi
Cold Case, Carlotta Carlyle #7, by Linda Barnes, $1.99
Kindle US:
https://www.amazon.com/Cold-Case-Car...dp/B00XV8A24M/
This Side of Murder, Verity Kent #1, by Anna Lee Huber, $2.99
Kindle US:
https://www.amazon.com/dp/B01N4JS4N4
Kobo US (discountable):
https://www.kobo.com/us/en/ebook/this-side-of-murder-3
Treacherous Is the Night, Verity Kent #2, by Anna Lee Huber, $2.99
Kindle US:
https://www.amazon.com/Treacherous-N...dp/B078QSYZ3H/
The Homicidal Virgin, about halfway through the Mike Shayne series, by Brett Halliday (one of the Brett Hallidays), $1.99
Kindle US:
https://www.amazon.com/dp/B013CUC1L0
Kobo US (discountable):
https://www.kobo.com/us/en/ebook/the-homicidal-virgin
Ragged Lake, Frank Yakabuski #1, by Ron Corbett, $1.99
Kindle US:
https://www.amazon.com/dp/B071CX8MYG