Three JK Rowling “Hogwarts Library” books, which are tie-ins to the Harry Potter series, and are usually mentioned (or even essential elements) in the main seven books, have dropped in price right now, both in the US and the UK.
Fantastic Beasts and Where to Find Them (not the original screenplay)
Kindle US, $1.99: https://www.amazon.com/dp/B01LYBG60A
Kindle UK, £1.99: https://www.amazon.co.uk/dp/B01LZY70SV
Quidditch Through the Ages
Kindle US, $1.99: https://www.amazon.com/dp/B01F3ET2QU
Kindle UK, £0.99: https://www.amazon.co.uk/dp/B01F3ET2SS
also at Kobo US, $1.99: https://www.kobo.com/us/en/ebook/quidditch-through-the-ages-4
The Tales of Beedle the Bard
Kindle US, $1.99: https://www.amazon.com/dp/B01F3ET2SI
Kindle UK, £1.99: https://www.amazon.co.uk/dp/B01F3ET2RE
I’ve not seen any of JK Rowling’s Harry Potter books go on sale quite this cheap, and no idea why it’s the second one, and not the first one (to hook people), but here you go: Harry Potter and the Chamber of Secrets for $2.99 at both Kindle and Kobo US.
But I already think it’s pretty cool of Rowling to put them all in KU anyway…
Kindle US: https://www.amazon.com/dp/B0192CTMW8
Kobo US: https://www.kobo.com/us/en/ebook/harry-potter-and-the-chamber-of-secrets-6
And now for those in the UK…the first two in the series are now £1.99 at Kindle UK. Possibly as part of the UK monthly deal ???, but not sure, so I’d grab them if you want them…
Harry Potter and the Philosopher’s Stone (apa in the US as Harry Potter and the Sorcerer’s Stone)
Kindle UK: https://www.amazon.co.uk/dp/B019PIOJYU
Harry Potter and the Chamber of Secrets
Kindle UK: https://www.amazon.co.uk/dp/B019PIOJY0