Last I checked (some years ago), no one in the US offered true insurance for rabbits. They had plans that took a monthly premium and basically acted like a savings account without interest, though... but it wasn't actual "insurance."
Not sure if that's changed. I've heard places in Europe offer real insurance for rabbits.
Well there is Nationwide pet insurance and they have a plan that covers exotics. I heard it covers the most things out of all the pet insurances and I think it covers routine exams but I don't know for sure.
I have Nationwide for my two. It is $12 a month per bun, and luckily they had no preexisting conditions. My girl just spent 2 days in the ICU and 2 outpatient visits, over $2500. So far Nationwide has reimbursed me about $700. It's not a lot, but seems to be a good deal since I only spend about $120 a year on the policy.