Kobo US is having a $2.99 sale this weekend, good through Monday, Feb 4 (although Kobo's sales sometimes end early). Most are also VIP/couponable. The sales page has a group of Thriller titles and a Crime & Mystery group.
Most of the titles in the Collins & Burke series by Anne Emery are $2.99 each, including an omnibus of the first three titles, which works out to a pretty good price each if you need all three. Link:
https://www.kobo.com/us/en/search?Qu...9&fcmedia=Book
Other authors I recognize with one or more titles: Lee Child, Michael Crichton, Jack Higgins, Carl Hiaasen, Ruth Rendell, Marco Vichi, an omnibus of Albert Campion titles by Margery Allingham, Ellery Queen, George Bellairs, James Ellroy, Dorothy L Sayers, Peter James, Ellis Peters (Felse), Patricia Wentworth, Charlaine Harris (Aurora Teagarden), Anne Perry, Quentin Bates, William Deverell, and John McFetridge.
link to overall sale page:
https://www.kobo.com/us/en/p/299for2...=00003&utm_id=