Bob,
I don't have numbers for an '83 boat, but maybe this will help. Thge orginal base price for a new, 1978 M-382 was $48,900. In July, 1979 the base price had jumped to $59,950. My boat, hull #179, sold for $64,374, including a bevy of popular options -- including roller furling, swim ladder, bimini, dodger, bow roller, hot water heater, second water tank, and a dozen or so more. With a little luck, maybe you can use the cost of living figures for those years and extrapolate close to the cost of a 1983 model.
Good luck...