Today's Big Deal at Kindle UK is seven Hercule Poirot books by Agatha Christie for £0.99 each. Be aware, one of these,
The Murder on the Links, is public domain in the US at least (and probably lots of other countries, given how draconian US copyright is) and you can find it at
Project Gutenberg and other PD sites.
link to the Big Deal webpage at Kindle UK:
https://www.amazon.co.uk/s/?node=4725112031