None of my "mature" riding friends pay more than $1000/yr. For their litre+ bikes.
anyone not paying $1000+/yr for a modern superbike has likely either been riding a 'long' time with a clean record or they live in Narnia
other kinds of 1000cc+ can lean more to model specific risk profiles.
What @Evoex said - I'd sure like to see the details on those policies as that seems ridiculously low. I think the cheapest insurance I ever had was $600/year on my old VTX and that's with all my years of experience and insurance history, and I'm no spring chicken. To be <$1K/year on a litre bike seems unfathomable.