I used the AIG (before it was branded Barrett Jackson) for years. When I had my Cobra they covered the GT at a very favorable rate. Once I sold the other cars the GT rate went to $1/1000 of coverage. Their policy is that if you have older cars that the new cars are then covered at the same rates, but without the older collection to go along the rate is adjusted. It turns out that their rate was competitive when I was in CO, but after we moved to NV Drw saved me about 1/2 over AIG.
My point here is that you should shop around and compare rates (and coverage!) from several places. Location really does matter.