Kobo US has a buy 1/get 1 sale through Jan 11. In the "Thrilling Mysteries" section there are a lot of books by a couple of authors I like - Edna Buchanan (police procedurals set in Miami) and Candace Robb (historical). And the "base" prices are pretty reasonable to start with...mostly $2- $3.
Also books by Gary Grossman, Bradlee Frazer, Lynne Heitman, Grant Blackwood, Mia Thompson, Newton Thornburg, David Dodge (including
To Catch a Thief, basis for the Hitchcock movie), and Kate Riordan.
Too many books to list individually, but sale link is here:
https://store.kobobooks.com/en-us/li...V8ykRAjTCzur-g
Added note: There is also a Buchanan/Britt Montero omnibus that contains several of these titles - depending on whether you have some titles already, the omnibus might be a better deal, even not on sale:
https://store.kobobooks.com/en-us/eb...mnibus-edition