Android market DOESN'T do recurring billing... The $30 is a one time fee per Google Checkout acct (meaning the app will follow you to any other Android device using your same Google checkout acct)...
I'm using it from a marginal 3G (sub 500K) and it worked REALLY good on two Slingbox classic devices.
It warns that it won't work on Classic in most cases, but works fine with me... just ensure your classic boxes have firmware updates.
Screen shots attached..