Re: moisture at one shroud
The repair could be essentially free (except for labor) if there's just a little leakage around the chainplate and little or no core saturation. Just rebed the chainplate and stop the leak.
It could cost more than the boat if there's a lot of core saturation. You also need to be sure that if the chainplate was leaking, the chainplate attachment to the hull is still structurally sound.
Really, if you're serious that THIS is the boat, hire a surveyor.
1977 C&C 30 Mk 1 hailing from Port Clinton, Ohio