AppStore revenues - is Morgan Stanely wrong?

I estimated the revenues generated by the AppStore (considering 30% commission, an avg. price per paid app of US$ 2,89 and 3,37 apps downloaded per month per device – including iPhones, iPod touch and iPad and establishing the 1,9 bn. downloads at September 2009).

To estimate the number of paid apps downloaded I used a figure from AdMob stating 16,3% of downloaded apps are paid by customers.

The results: US$ 103 million in revenues for Apple in the past quarter (vs. US$ 17 million estimated by Morgan Stanely, representing 16,5% of my estimates)

Using Morgan Stanley estimates only 0,8% of total apps downloaded are paid apps…seems bit low to me!

Find attached excel model: AppStore revenues model

[Via http://aconsideration.com]