How to start a magazine and make a profit

Jacob Goldstein's on Marco Arment's magazine, The Magazine:

"What I saw was a fluke in app store pricing," he told me. "If you have an app, you can charge, realistically, about $3 these days." Somebody buys the app, and that's it. But for a magazine, you can charge $1.99 every month.

Impressively, The Magazine already has 25,000 subscribers and turns a profit of $15,000 every month.