Dew,
Liberal analysts argue that about 30% can be saved from healthcare just in administrative costs, if a public option is available. That squares nicely with your figures. Even though some right-wing ideologues on this board refuse to acknoledge it, Medicare is three to ten times more administratively efficient (depending on which analysis you go by), cost-wise, than the private insurers. I have not seen one single thoughtful conservative economist dispute these numbers.
Bladerunner