I pay $15.60 per month for full coverage on my 2004 Saab 9-5, which includes liability of $500k. One of the benefits of living in Ohio, which has about the cheapest insurance rates in the country.
I also have a 1989 Porsche 944S2 (totally unmustachian I know), and that is even cheaper at $13.35 for full coverage.
I'm with Grange insurance.