I am with USAA and medic09 is right, they farm out bike insurance to Progressive. I've got three bikes on there for $200-ish a year altogether, and I think that's damn good compared to my car insurance. Five to Seven bucks a month per bike is not bad at all to me, especially considering the insurance my peers are paying on new bikes*.
Of course part of that is that the car is still being paid off and as such, I have to carry every insurance known to man on it, while on the bikes, I only have the minimum liability to get them on the road legally. It's just not worth it to carry tons of insurance on old machinery. I got burned on this on an old car. If something happens, they NEVER give you the actual value, but instead some bull#$%* out of a book and a formula.
*: I have a soldier who just bought a Hayabusa cash with money from an insurance settlement. He has a less-than-stellar driving record, so his insurance payments are, wait for it...$360 per month!!!