You DO pay a premium to get Buffett/Munger as money manager. You also get Buffett as investment superstar. No one has better connections. No one can borrow money cheaper. No one refuses to take a phone call from them.
Once you pay the upfront premium to buy BRK shares, the "boys" work dirt cheap. $100k each per year spread over 80 enterprises.
As WB says: "You can trust us not to do something stupid with your money."