Same on UK Amazon

https://smile.amazon.co.uk/Plant-Based-Diet-guide-longevity-ebook/dp/B079N27FZF/ref=tmm_other_meta_binding_title_sr?_encoding=UTF8&qid=1518382856&sr=8-2

It's less obvious since Amz unlimited is the default but clicking buy got me £0

Also - please use Amazon smile links - results in "free" charity donations:

http://smile.amazon.co.uk/

http://smile.amazon.com/