I highlighted Jordan's new app Spend Stack recently and he now has a follow-up post on his app launch. When Jordan decided he wanted to launch Spend Stack as a paid app, he looked to apps that have had success with this type of monetization. He modeled his app after those apps.
You'll also get his list of launch tasks. Quite handy if you have a launch coming up any time soon.
On Launching Your Indie App by Jordan Morgan