My Mom was looking for good SF or Fantasy books, cheap FREE. So I compiled a list, with links, for her.
On Basilisk Station, by David Weber
Oath of Swords, also by David Weber, one of the best Epic Fantasy series out there.
A Hymn Before Battle, by John Ringo, excellent military SF
1632, by Eric Flint, rollicking good alternate history
Draw One in the Dark, Sarah Hoyt, urban fantasy fun
In the Heart of Darkness, David Drake and Eric Flint, for more alternate history, Roman this time.
The Forlorn, Dave Freer, space opera by one of my favorite authors.
All Cats are Grey, by Andre Norton
The Answer, by H Beam Piper, and any others by him you can find!
Ham Sandwich, James Schmitz, classic SF
Drums of Jeopardy, the book from which Boris Karloff may have drawn his name. Pulp fiction
The Insidious Fu Manchu, by Sax Rohmer, more old school pulp fiction.
The Moonstone, Wilkie Collins, one of the first detective novels.
The Wonderful Wizard of Oz, L Frank Baum, a perennial favorite of mine.
The Mysterious Island, Jules Verne, my favorite Verne book.
Rikki-Tikki-Tavi, Rudyard Kipling
A Princess of Mars, ER Burroughs, more classic SF/Fantasy fusion
I may add more later, Mom, but this should start you! And my readers, suggestions in the comments are always welcome, she isn’t interested in Paranormal Romance, or “adult” themed books.