Georgia State Parks charge a $5 parking fee or you can purchase an annual "Friends of Georgia State Parks" annual pass, $70 for 12 months regardless of when it is purchased and for state senior residents the pass is 1/2 price, $35 which includes one night of camping. The pass gives seniors a 20% discount on camp sites, historic parks may or may not give a discount.
COE campgrounds are managed by volunteer hosts so some may not enforce the rules as they should. Usually with the America the Beautiful pass all that is required is that one person in the vehicle have a pass, does not have to be the driver.
You can't beat the COE campgrounds for price. Gunter Hill COE on the west side of Montgomery, AL has full hook ups in the new section at $13 per night. Cost for camp sites will vary with the campground. The rules are governed by the CoE district they are in.
2014 Palomino Puma 25RS
2011 F-150 Super Crew XLT
Days camped in 2014 - 23
Camped 2015 - 47
Camped 2016 - 51 done - 6 more planned so far