Humble is best known for its game bundles, but it also packages applications and other media at discount prices from time to time. For example, right now it's running a book bundle containing digital sci-fi novels penned by actual scientists, starting with six titles for $US1.
I can't say if the featured authors / scientists are any good on the narrative front, but at the very least they'll be accurate. Fortunately, if you're interested, you can start by spending a single dollar (well, $1.30 or thereabouts) and sampling the following books in the bundle's entry tier:
The Protos Mandate: A Scientific Novel Nick Kanas A Man From Planet Earth: A Scientific Novel Giancarlo Genta On the Shores of Titan's Farthest Sea Michael Carroll The Hunt for FOXP5: A Genomic Mystery Novel Wallace Kaufman, David Deamer The Hunter: A Scientific Novel Giancarlo Genta Beyond Human: Engineering Our Future Evolution Erik Seedhouse
If you find those enjoyable, you can spend another $US7 to get six more:
The Return of Vaman: A Scientific Novel Jayant V. Narlikar The Caloris Network: A Scientific Novel Nick Kanas The New Martians: A Scientific Novel Nick Kanas Small Doses of the Future: A Collection of Medical Science Fiction Stories Brad Aiken Murder on the Einstein Express and Other Stories Harun Šiljak Alien Encounter: A Scientific Novel Dirk Schulze-Makuch
Finally, spending a total of $US15 gets you everything, include these four books:
Using Medicine in Science Fiction: The SF Writer's Guide to Human Biology H. G. Stratmann Hollyweird Science: From Quantum Quirks to the Multiverse Kevin R. Grazier, Stephen Cass If the Universe Is Teeming with Aliens ... Where Is Everybody? Stephen Webb Exploring Science Through Science Fiction Barry B Luokkala
As with most bundles from Humble, you can contribute varying amounts to charity, Humble or the publisher, Springer Nature. And there's no rush -- at the time of writing, it'll be around for another 10 days.