I was going to say "Brendan O'Brein" and "Southern Tracks" until I saw the terms "reasonable rates" and "hip hop". Sorry, I don't know who to recommend for you.
I "know" Steve from online only, but he's always come across as being very nice and very knowledgeable. I forgot that he was in Atlanta... and I didn't realize he worked on rap. I would have suggested my friend Lee Flier too, but she's more into rock and retro stuff. Great engineer though, if anyone down in 'lanta needs those services.
yeah! Tree Sound Studios! check out the site: It's the best studio in Atlanta. Just look at there client list, they have recorded some of the biggest acts in hip hop and R&B