The fifth movie is one of my favorites because it portrayed a lot of libertarian leaning ideas. Mises did explain, as I have said in my post about Fringe, that it is expected for statist ideologies to be very prevalent in literature and that's why I get really ecstatic when I see ideas about the benefits of less government in mainstream media.
Diagon Alley is a place where people can voluntarily exchange and trade with each other. Government intervention is probably so minimal or perhaps even non-existent. I don't think there's a lot of red tapes or requirements or unnecessary permits to start up a business there. The Weasley twins were easily able to start their own magic hobby shop place easily. Real prices arise, competition encourages innovation, and people are able to find the best ways of serving one another.
Sadly though, she's a left-wing socialist J.K. Rowling donated 1 million pounds to the Labour Party and is a good friend of Gordon Brown and even praised him in an essay in TIME magazine. She's also an advocate of a welfare state and highly praises their NHS.