We haven't camped there, but we've been to the Outer Banks many times.  We've always heard that Ocean Waves Campgound is very nice and also very reasonable.  They actually have trees - which are a rarity on the OBX.   When we purchase our 1st fiver (spring next year) we will be planning a trip to the OBX and will most likely stay at Ocean Waves. 

When you are there - make sure you take a trip down to Ocracoke, one of our favorite places.  You have to take the ferry there from Hatteras, but it's a sleepy little village at the southern end of the island - with some great restaurants (the Backdoor) and some interesting shops.  The majority of the island is national seashore  -13 miles of unspoiled beaches.  We spent a whole day on the beach fishing and reading and never saw another person.    There is a national park service campground on Ocracoke - but no hookups.  There are a few other campgrounds on there to mention, but we've driven by and they look just ok. 

It's a wonderful place especially in the fall - just keep an eye out for hurricanes.