The third through tenth titles in the Charlotte and Thomas Pitt series by Anne Perry have dropped to $2.99 at Kindle US. For the moment, at least, not on sale at Kobo US. The link includes a few strays - a couple of Anne Perry titles from other series, and some other strays towards the end. I'm in a hurry and don't have time to clean it up, but the Pitt titles are all near the top, at least for me...
link:
https://www.amazon.com/gp/search/?ta...price-asc-rank