@Stooky: I don't understand your math. You don't need to sell 1000 premium membership yourself, you just need 1000 downloads from Premium users group A.
I realize that but it is still practically an impossibility. Chances are no doubt there aren't 1000 premium members who all live in Group A who are all downloading the same individuals files. I'd say 99% are free users as with most hosts.
The average earnings for anyone is $15 per 1000, not $30 per 1000 because that requires premium accounts which is not a guarantee. The $15 per 1000 is a guarantee because anyone can download files from that earnings bracket.
Don't get me wrong though, it isn't just your host, this goes for many hosts across the board.