This question is worth everyone's attention
Whether the other two who answered (Top Contributors no less!) are referring to Key Limes or just Limes is an unknown item. However, in Atlanta you can go to the Produce Department at any Publix Supermarket and get Key Limes. If they are not on display you can ask the Produce Manager to order them for you and provided the Key Limes are available the Produce Manager will have them in stock for you within a week. Do you need Key Limes or just the juice for a recipe? If it's just the juice then you can order it direct from the source. I've posted the link for Nellie Joe's Famous Lime Juice. They are located in Key West and have an abundance of products from real Key Limes.
Don't you have limes in your grocery stores in Atlanta? Check the fruit and vegetable section or ask the store manager where they are. Out here on the West Coast, we have them in abundance, FYI. The grocery chains probably don't want to pay the shipping costs I bet, since most of your fruit was grown down in Florida and got frozen. Most limes come from Texas, Mexico and California.
the nellie and joe's key lime juice is available at publix. i have bought it there when making key lime pie-it even has a recipe on the label!