Fifteen Kinsey Milhone titles by Sue Grafton have dropped to $2.99 at Kindle and Kobo US. These are the early ones - letters A through O. So if you need to do a little filling-in, now might be the time!
Kindle US:
https://www.amazon.com/gp/search/?se...price-asc-rank
Kobo US:
https://www.kobo.com/us/en/search?qu...9&pageNumber=2