Several titles in the Hawker thriller series by Randy Wayne White, written using pen name Carl Ramm, have dropped to $1.99 each at Kindle US, as well as an omnibus of the first three titles at $2.99. There's also one early Doc Ford title,
North of Havana, at $1.99 right now, both at Kindle and Kobo US. I've read and liked some of White's Doc Ford titles, but have never tried the Hawker series, which looks a little more thriller-ish than I usually like. But at $2.99 for the first three, I'll probably try the omnibus.
North of Havana, Doc Ford #5
Kindle US:
https://www.amazon.com/gp/product/B00AFY34PE/
Kobo US:
https://www.kobo.com/us/en/ebook/north-of-havana-1
The Hawker Series Volume One: Florida Firefight, L.A. Wars, and Chicago Assault:
https://www.amazon.com/dp/B074Q6TDBN
Florida Firefight, Hawker #1, by itself:
https://www.amazon.com/gp/product/B016LP32Z2/
(Note that this title was also part of a Humble Bundle a while back, so check carefully if you're thinking about buying this, or the omnibus above.)
Deadly in New York, Hawker #4:
https://www.amazon.com/gp/product/B016LP337O/
Vegas Vengeance, Hawker #6:
https://www.amazon.com/dp/B016LP333S
Denver Strike, Hawker #10:
https://www.amazon.com/gp/product/B016LP32L6/