I know something about the pricing dilemma because in addition to working on the Windows Phone Store business team, I’ve published more than 20 apps in the Store myself, many of them paid. In this post I’ll explore some of the things I consider when trying to determine the best price for my own apps, and share some suggestions on how to take advantage of Dev Center’s pricing and analysis features.
There are lots of numbers to go over here, and some good advice on how individual developers should approach the pricing of applications. It should be no surprise that there isn't a single answer, but Zamora's approach is one that can be followed by many.
Do remember that a paid-for download is just one way that apps can bring in income to a developer - in app advertising, freemium models, and subscription based services are all valid alternatives. But if you have went down the paid-for route for your application, Zamora's strategy is a good place to start.
The full article, with graphs and charts, can be found on the Official Windows Phone Developer Blog.