I have Allstate and pay $271.41 / year for 100000/300000/100000 liability and 500/250 deductible collision/comprehensive but no UI/UM (stacked UI/UM on my 3 cars and in FL that carries over to all other situations). UI/UM in FL will triple the costs.
2 things to check.
1. Make sure they rate it as a Sport Touring bike and not a Sport Bike or a Trike. My agent changed the class and the rate was cut my more than half and underwriting accepted it but their default is still Sport Bike, AKA a 1 liter race replica.
2. Give the guys at Fisher Insurance a call. They did exactly what I did and fought with their primary carriers to get Spyders rated properly. Their quote was within $20 of what I pay but I have 2 other bikes with Allstate so it wasn't worth the switch.
http://www.bikersins.com/spyder_ryders.html