There isn't a J/30 that's less than 25 years old at this point, so all have been in the water for many years. (Except one I know that lives in a Quonset hut in PA, but that's another story.) If you're in the market get it hauled and surveyed. See what, if any repairs are likely, then compare to others available. You might want to search the Boat, Sails and Equipment forum or read the several blogs of owners who have done extensive repairs.