Some people have mentioned that you automatically get $1M liability coverage on a small boat in most home insurance
packages, so be sure to check yours or ask your agent. And I think there's trailer coverage in the auto insurance.
Our club requires us to carry $2M liability so we have a separate policy. It includes replacement coverage, towing and other stuff. Our company is Aviva Elite... have never made a claim so I don't know what they're like there. I would guess a separate policy for you would run roughly between $200 and $300 per year.
Ask your home insurer or a broker if they have a marine
underwriter they like to work with.