What is the best price for an iPhone App?

"In a market of 100 Million devices (in june) I only need 0.005% of all iOS device owners to buy my App at $2.99 to make a reasonable amount of $9,867."

I think you need to think more about why even one person would buy your app at any given price. What about looking at similar apps that are grossing well rather than just the broad general market of top grossing apps?