Kobo has a start a new series for up to 85% off deal, available until 24 January according to the webpage
https://www.kobo.com/us/en/p/startanewseries
The options this time seem to include a large number from traditional publishers.
For example in the “Otherworldly Science Fiction & Fantasy” section I have found books from Anne McCaffrey, Jack Campbell, Anne Bishop, Jim Butcher, Ilona Andrews, Patricia Briggs, Charles Stross, Guy Gavriel Kay and many more authors which I enjoy.
I’m not sure if these are publisher specials or kobo specific but this sale is worth looking at.
There are also sections for mystery, romance, kids and YA