Kobo is holding a weekend 99¢ sale. These sales are usually dominated by self-pubbed and small-press titles -- and that's the case here, too -- but if you cursor down to the Science Fiction section you'll find World Without Stars, by Poul Anderson, and The Sheep Look Up, by John Brunner.
World Without Stars in particular is an old friend that I was happy to find again! (But I really preferred the original Ace paperback cover illustration!)
It's a weekend sale, so it's good for just 4 days. The sale listings start here:
https://www.kobo.com/us/en/p/99sale18