State Farm insured my Xflow Caterham for 5 years, ending in 2011,then my Birkin for 2 years, ending in 2013. Must be that state-to-state thing Croc was discussing.
I dont have insurance on my current Caterham because it is, as they say, actually a race car. So never driven on the street.
Cost was same as my other older cars. I got a price break because didn't (typically) drive over 5,000 miles a year.