It was suggested in another thread that we add an option for a league that only players who have a credit balance of 6 or more be allowed to participate in. This would mean that all users would be required to purchase credits, essentially making it a "premium" league. The advantage would be that the users in the league would likely be more engaged since they actually paid to play, and hopefully it would also result in lower league turnover as a result.
If this interests you, please post your interest in this thread. If I get 20 takers, I'll create the new league type and launch it. Also specify whether you would prefer a standard league or a custom league - and whether you would join if the type you prefered were to get fewer votes.
Consider also that if you purchase credits, your balance will not be refreshed unless it falls below 5 - so if you participate in multiple leagues, you will essentially be paying to remain in those leagues as well.