The quotes seem to vary from company to company. For Eg: I saved a lot of money when I switched from Statefarm to Geico while a buddy of mine saw a significant decrease in his premium after switching to Statefarm from Geico. If you really want 'cheap' insurance, try finding a local insurance company whose coverage is limited to a certain area (like the city you live in). 

By the way, 200 is too high for full coverage, let alone 250. Didn't consider insurance premium before buying 7-series, huh?