[oh8eleven]

private insurance company [like AARP (shudder)]
Wrong. AARP is in NO WAY an insurance company.
Medicare Advantage programs (I'm on one too) are run by private insurance companies and supported by gov't money. I'm 95% sure Supplemental Plans are as well, but I'd have to research them agian to be sure.
The Supplemental Plans run from $50 a month to over $400 a month depending on a number of factors.

[Bob Ireland]

***Wrong. AARP is in NO WAY an insurance company***

Check the ownership - or control - of United Healthcare.