Currently available cheap in the US and maybe more broadly and more longly but not likely so:
Three Hearts and Three Lions by Poul Anderson cheap for Kindle*
The Complete Brigadier Gerard cheap for Kindle* by Arthur Conand Doyle (not Sherlock Holmes stories).
The original novel MASH* also cheap for Kindle.
Everybody but you read this when it first came out, now is your chance to do it cheap: SYNC*
Nice. I have a link to the top 100 free kindle books in Science Fiction and Fantasy on Amazon:
https://www.amazon.com/Best-Sellers-Kindle-Store-Science-Fiction-Fantasy/zgbs/digital-text/668010011/ref=zg_bs_nav_kstore_2_154606011?_encoding=UTF8&tf=1
You can use the categories to the left to browse to the top 100 free kindle books in any category.
I peruse this daily and then buy the free books I might like to read, so they are in my library and I can download them to my kindle whenever I want to read them.
Free is even better than cheap! So check it out.
What is the final link (“sync”) supposed to be?