We got married in Tybee Island on the beach, then the reception was at the guard house, with about 50 people. We had BBQ catered (Sticky Fingers in Savannah). The whole thing, with week long honeymoon ran us about $5k.
The guard house is awesome because they let you BYOBs, which kept the price down, and you rent the thing for $600.
This is the Guard house:
It's basically 2 rooms, one for dancing (wood floor) and one for eating (tiled), small kitchen, large wrap around porch (where we held our cocktail hour)
I can't recommend Sticky Fingers enough, either! Awesome food and Kym (catering manager) is AWESOME! We paid $8 pp which was pulled pork, 2 sides, and tea, lemonade and water.
Savannah, GA - (912) 629-6299
7921 Abercorn Street, Savannah
A good site for nice, fake, flowers is afloral.com
If you're at all interested in doing it in Tybee, LMK, and I can basically walk you through it.
The only thing I probably wouldn't recommend is doing it ON the beach, unless you do it at night--lots of fat dudes in speedos LOL. But maybe you could do it at the lighthouse instead:

It's about a 4 hr drive from Atlanta, btw.
EDIT--Just wanted to add that everyone who came from EAV was like "This is like EAV on the beach." And everyone LOVED the location (even uppity in laws, lol). I can't tell you how much we love Tybee.