I would allmost say the same as T3AR but I suggest that you use serial codes instead, also please make sure that you can pay with phone and dont push the price throw the roof either, idea is that you send a message or call some number, it charges you the money and then sends a serial with sms or you send a message to a number with your username, it charges you the amount it needs and then your account is acitvated and you are ready to roll.
That is what I think, if you could only pay with credit card and paypal then I wont be playing this game for a long long time, I have a credit card but im not 18 so I cant use it to buy stuff online.