Could anyone point me in the right direction for downloading app store statistics from:

-the Apple App Store -The Android Market -the Amazon AppStore

Specifically, I'd like to get the

-average selling price of apps -the top selling apps -the distribution of tablets vs. phones, etc. -total number of apps in store -free vs. paid apps

I've seen some sites like http://148apps.biz/app-store-metrics/

and http://www.appbrain.com/stats/

How do these sites get their data? There must be a way to export the whole app store database as a CSV file, or import it to MySQL and run queries.

Thanks much for any direction.