You're in luck. Insure.com can assist you. From the company's press release:
Insuring a bling machine can get expensive if you want to be fully covered for the modifications you've made. Let's say you want to insure a '93 Toyota Supra that you bought for $7,000. It has a 600-horsepower engine, custom paint job, spoilers, ground effects, custom wheels, a highly customized interior and roughly $30,000 worth of stereo components. You poured around $130,000 into the car. Your estimated annual premium would be $2,000 to $2,500 -- and that's assuming you have a clean driving record.