All seven books in Adrian Magson's Rocco series are £0.99 each, except for the second, which is £1.99. Several of these are new price drops, but some, like the first, are long-term-ish prices. The titles are:
Death on the Marais,
Death on the Rive Nord,
Death on the Pont Noir,
Death at the Clos du Lac,
Rocco and the Nightingale,
Rocco and the Price of Lies, and
Death at the Old Asylum. Here are links to the series webpage:
Kindle UK:
https://www.amazon.co.uk/dp/B09GF6GR...kindle_edition
Kindle UK/Smile:
https://smile.amazon.co.uk/dp/B09GF6...kindle_edition
And, if you prefer to shop in the US, the first two are $0.99 each and the remainder are $2.99 each, except for the sixth one, which is $3.99 right now. But still not too bad on the pricing. And here are links for the series webpage in the US:
Kindle US:
https://www.amazon.com/dp/B09GF6GRQZ...kindle_edition
Kindle US/Smile:
https://smile.amazon.com/dp/B09GF6GR...kindle_edition
And finally, the novella,
Rocco and the Snow Angel, is £1.99/$2.99 in the US/UK, although that seems a bit expensive to me for 58 pages...
Kindle US:
https://www.amazon.com/dp/B08P4BJ7W6
Kindle UK:
https://www.amazon.co.uk/dp/B08P4BJ7W6