Maybe a solution would be something similar to the babydolz store, where you can buy gift cards and jokers from time to time. Add the option to buy them with credits or credit card and a possibility for the EX cards, too.

Actually I'm not totally against games, when the chances are fair.

And I really appreciate the possibility to get EX cards at a later time again, in case you missed the event, had to skip it or are new to istripper. I think that's a step in the right direction, even if you still can improve the ways how to get them.