I got screwed on a Fan Fic once for a Tudor book. I was pissed - as I paid a regular price for one of the worst books I have ever read and it was a real book, not an eBook.
Amazon doesn't police their stuff very carefully. I think if stuff is self-published or by a vanity press, it should say so very clearly.
Needless to say, I'm very careful now when ordering books and I do check publishers.