This paper discusses the economy that exists in the Harry Potter Books. The most interesting conclusion (which would make a good extra credit assignment) was this.
This implies that the factors of production (physical capital, human capital and
labor force) and the technology which could potentially drive economic growth remain
unchanged in the Potterian economy. As a consequence, the wizards’ economy remains
in a steady state without growth.
In the real world the economy grows and has been for hundreds of years. But in our fiction we keep things stagnant...interesting.
Marginal Revolution has a post on JK Rowlings earnings, tying it into inequality.