This is clearly promotional – flagged as spam.
Why? It’s not spam. They’re a member of the community.
I haven’t looked into whether their work is good or not, but it seems unfair to judge it solely on the basis that they’re asking for money. More devs should charge for their work.
It seems like self promotion is ok as long as it serves a community interest.
Six of his last ten submissions were for this specific book, with what looks to be the same page. It’s not flagged as “already posted” because he’s changing the url parameter.