Several tordotcom novellas are $1 at Amazon US (links below) and probably Kobo US right now:
Permafrost Alastair Reynolds, confirmed at
Kobo US
Void Black Shadow Corey J. White
Her Silhouette, Drawn in Water Vylar Kaftan
Everything Belongs to the Future Laurie Penny
Sunset Mantle Alter S. Reiss
I've read the Reynolds and the Penny and found them worth the read. Sorry I ran out of time to confirm the other links, Friday plans are calling.