Three books in Seanan McGuire's October Daye series are $1.99 in the US right now - the first, the second, and the fifteenth (and next to most recent). This series doesn't go on sale very often in the US, so grab them if you want them.
Rosemary and Rue, #1
Kindle US:
https://www.amazon.com/dp/B002N83HAW
Kindle US/Smile:
https://smile.amazon.com/dp/B002N83HAW
Kobo US:
https://www.kobo.com/us/en/ebook/rosemary-and-rue-8
A Local Habitation, #2
Kindle US:
https://www.amazon.com/dp/B0030CVRDE
Kindle US/Smile:
https://smile.amazon.com/dp/B0030CVRDE
Kobo US:
https://www.kobo.com/us/en/ebook/a-local-habitation-3
When Sorrows Come, #3
Kindle US:
https://www.amazon.com/dp/B08WHXWSM3
Kindle US/Smile:
https://smile.amazon.com/dp/B08WHXWSM3
Kobo US:
https://www.kobo.com/us/en/ebook/when-sorrows-come-7