If we did add another (jeez) donor rank, it would probably be a complete redistribution of all perks, with some new, lower power, perks seeded into the lower ranks.
Fly and 2x XP are already strong enough, 3x money is more than anyone should have, and trying to "outlaw gm items from being sold" is just naive. We can "outlaw" whatever we want to, doesn't make it possible to control.