Not technically a sale, but a new omnibus:
Terrible Worlds: Revolutions by Adrian Tchaikovsky is $7 on
the publisher's web store
This collects the thematically-linked novellas
Ironclads,
Firewalkers, and
Ogres, each is currently $9 on its own - perhaps the individual prices for these novellas in the same store will be reduced at some point.
Ogres is hyped up by everyone who's read it.