Smashwords (
https://www.smashwords.com) has their summer sale posted running throughout July. It's the usual morass of self-published works with a smattering of back-list titles where the rights have reverted to the author.
Of note:
Ruthanna Emrys:
Imperfect Commentaries is $3.50 (50% off)
https://www.smashwords.com/books/view/946158
Very recently published short story collection not available on Amazon (at least in the UK).
CatYelling (publishers) have a number of titles by Will Shetterly & Emma Bull. Not in the sale, but they tend to be cheaper than Amazon:
https://www.smashwords.com/profile/view/willshetterly
I've picked up electronic versions of various titles (I already have
Liavek in both electronic and print - note that the electronic versions differ because of rights).
Lavie Tidhar (
https://www.smashwords.com/profile/view/lavietidhar) is currently 50% off in the sale. The 4 Apex World SF books (one - #4? - was in a recent StoryBundle) are $2.50 each and a couple of novellas are $1.50 each and thus cheaper than Amazon.
Cynthia Felice:
Iceman is $2.00 (50% off):
https://www.smashwords.com/books/view/932976
Other authors with some titles in the sale:
Lee Killough:
https://www.smashwords.com/profile/view/killough
Melissa Scott:
https://www.smashwords.com/profile/view/melissascott (the Astreiant series)
Sherwood Smith:
https://www.smashwords.com/profile/view/SherSmith &
https://www.smashwords.com/profile/view/sherwoodsmith
Vera Nazarian:
https://www.smashwords.com/profile/view/VeraNazarian
Jeffrey A Carver:
https://www.smashwords.com/profile/view/starrigger
Chris Dolley:
https://www.smashwords.com/profile/view/ChrisFrancis
Ben Bova:
https://www.smashwords.com/profile/view/bova
Brian Herbert:
https://www.smashwords.com/profile/view/brianherbert2 (NOT a Dune sequel...)
John Dalmas:
https://www.smashwords.com/profile/view/johndalmas
Robert Silverberg:
https://www.smashwords.com/profile/view/silverberg
Sean McMullen:
https://www.smashwords.com/profile/view/seanmcmullen