If you can do it off-season, there are beach rentals. In the Eastern NC Craigslist, I had seen a camper for $400/month at Atlantic Beach. The rates go up after mid-April.
If you could work from the towns near Jacksonville (like Hubert), there are shares of housing like mobile homes. These are mostly geared toward military. Check the classifield in the Jacksonville Daily News:
Real Estate For Rent : ENC Classifieds