My buddy has 250 a month with NJ Manufacturer. Another buddy of mine is at 190 with Progressive, but he's also never had an insurance claim in his eleven years of driving.
Depends on your age and gender mostly when it comes to buying sporty cars. I know with my driving record, it would cost me 350 a month for a 300zx with NJ Manufacturers, which is pretty damn cheap considering I have three speeding tickets on my record.