For whatever reason the autobiography of Katherine Johnson, the NASA mathematician who inspired the book Hidden Figures, is just $2.84 at
Downpour.com The audiobook is $23 ish on audiible and $15 on the Google play store where audiobooks are regularly discounted. I checked it out from my library and was searching for a copy of Hidden Figures when I came across this. So far it's a fascinating story with excellent narration.
ETA: $22 on Chirp