See the green box on the right? You're in the wrong Amazon shop. Go to amazon.co.uk and search for his book there. This works at least on amazon.de (same green info box in the US-store).

Odd, I thought that might be the case and I clicked on the green box and it just took me to Amazon's UK homepage so I just assumed it was just a generic "would you like to shop at Amazon UK" link rather than something related to the availability of the item in question.

But if I search Amazon UK for the title it comes up correctly and I can buy it.

Pretty poor UX really.

Yeah, UX is really poor. I don't know why they can't put a direct link to the product there - or at least trigger a search for the product.

Why an ebook is available in Brazil (where I am) and not in UK is beyond my understanding.