I mentioned this in irc chat but just so it does not get lost: it would be really helpful to some players if they could subscribe to the game without using a credit card. The more variety, the better.
Basic suggestions: enable Paypal payment of subscription.
(1) one way is the way EA does it: people use Paypal to send one month payment to an email address at EA. Someone at EA reads the emails and replies with a game key code that is entered to restart subscription.
(2) Paypal also allows monthly subscription costs to be deducted automatically; read about it here.
Allow game time cards. These are basically cards with game time keys on them that people can enter at the login screen to keep their subscription going. You couldshipboxed time cards to stores to get product visability. You could also tie it to the reseller's program so that people could buy and resell the time cards on ebay. Again, advantage would be another venue for product visibility.