USAA, Geico, Progressive, Allstate
Geico was the cheapest for me, because I have no tickets :knockonwood:
Now if I had some tickets USAA would probably be cheaper...
Almost any insurance agency that covers automobiles covers motorcycles as well.
Another thing to keep in mind is that if the "crotchrocket" is an older model, if would probably be much cheaper to just have the state minimum vices full coverage. Especially if you plan on having a 500 dollar deductible. Unless you completely trash the bike in a wreck, its gonna be cheaper in the long run to use your own cash to replace parts broken from a minor "incident"