I added mine to my existing atv policy and it cost me an additional $58 a year for full coverage.
2 grizzlies, a honda 250ex, a kasea 90 and the Wolvy all with full coverage costs me less than $500 per year
I pay like $330 full coverage with uninsured driver for the wolverine and my 13 grizzly.
I think it likely varies a lot by state and what places there are to ride in them. I would think places with more nasty trails would have higher rates. Also they probably look at the figures if they've had a lot of claims in your area rates will be higher
I have full coverage $500 deductible for $168.20/yr or $14.02/month with American family insurance. 100/300/100K. I didn't opt in for the underinsured driver. I don't do a lot of group rides where a collision with another offroad vehicle would be likely. That includes liability for guest passenger and coverage for additional equipment.