If you don't want big commercialiazation and lack of amenities doesn't bother you, then Hunting Island State Park, 17 miles south of Beaufort, SC on RT 21, is a wonderful campground. They have everything but sewer hookup, is very quiet, serene and on the beach. We are heading there monday for a week. Rates are good, around $200 for 7 days, seniors and disabled vets get a 30% discount.
I am a native Carolininian and have camped the MB area a lot years ago but left because of the bustle. Hunting Island is one of the best IMO campsites on the ocean in SC. Lots of good stuff to do in historic Beaufort also. The campground itself, the folks there, and the atmosphere are all "laid back," easy to relax there.