This is a very expensive area, but there are some places with somewhat affordable housing. I'd look at Smyrna and Cumberland first. The apartments on Northside in Buckhead are a little pricey for a recent graduate.
Look at apartments off Spring Rd and Village Pkwy in Smyrna which are the most affordable in the area without being eyesores (I'd recommend between Campbell Rd and Atlanta Rd). It's a very safe area and the rent is much lower than the rest of the Vinings/Cumberland area. Examples are the "Highlands of West Village". There's also a linear park on Spring Rd and it's within walking distance of Market Village in Smyrna. You'll be looking at about $600-$700/mo for a 1br in that area, and around $800 for a 2br. They are almost within walking distance of the mall -- about a mile away and probably a short hop on the bus. The cheapest apartments are Galleria Courtyard on Spring Rd ($500), but they are low income, a bit of an eyesore, and there's a tiny bit of crime in there. There's some across the road that look a little better and I imagine they are the next cheapest. As you head down Spring Rd towards Smyrna center, they get more expensive.
spring rd, smyrna - Google Maps
If he has enough credit, or you're able to cosign, I'd look to buy a 2br 1 ba condo in the area after he's rented for a year because it'll be cheaper per month to pay a mortgage and assoc fee than rent an apartment, and it'll be stable. The 2br 1 ba condos off Village Pkwy and Spring Rd will run you only about $110k. Example condo communities in this area are Country Park, Countryside At Cumberland, and Hillsdale.
I used to live in a condo off Spring Rd and loved it there, but it was too small when we had a baby so we had to move and rent it out and we moved to a bigger house on the other end of Smyrna. I highly recommend living off Spring Rd.
There's also a POST apartment complex (Post Crest) right near the Cumberland mall but I don't know how much they cost. I can only assume they are a bit more expensive. There's also Post Woods off Cumberland Blvd near 75 is in the $800s for a 1br (I did a little research because I was curious).
I'd also look at the apartments off Windy Ridge near Interstate North (Post Ridge?) and some more off Cumberland Parkway near the Home Depot headquarters (Magnolia Vinings has some in the $800s). There's also some apartments on Spring Hill Parkway, Post Springs being very expensive (lived there in 2005) but there are a couple others in there that are less expensive, but I forget their names.
I'm just did a search and Riverside House Apartments off Power's Ferry look like the most affordable nice apartments in the area, but I don't know much about them.
I'd check out rent.com and I'd also recommend you head over to a place called Promove and have them help him out.