I have full coverage from BOAT/US on an I20. It's about $150/yr. My yearly memebership, which includes unlimited towing coverage (a bargain if you sail in the ocean) is about $90/yr.
I highly recommend you get both types of insurance, as they are very cheap (for cats, at least), and cover potentially large expenses. Check it out at
http://www.boatus.comSail fast and have fun,
Alan Thompson
I20 - San Diego
P.S. I tow my I20 with a 1982 Toyota Celica I bought 5 years ago for $1000. Needless to say, it has only liability insurance!