Some of this would depend on how you register your car too I believe.
For example:
I live in Ohio and my car is plated as a "historical" vehicle. This means she sees very limited duty, but.... I have the car insured for the value I choose ( within reason, you have to proove if it's worth say a million ) through State Farm with my daily drivers and the insurance is VERY reasonable ( due to the limited driving duties ).
I would stand behind my agent because afterall he insures the "collector" vehicles not only for myself but my brother and my uncles.
I hope this sheds some light.