The national average for a return on investment is 75 cents on the dollar. The ROI is lower in Georgia, so you can reasonbly expect 65 cents for every dollar you spend.
The appraisal value of a finished basement in the state of Georgia would be between $25 to $35 a squarefoot. For a walkout basement, then $50 or $60 a squarefoot.
Only house portion "above grade" is counted. "below grade" portion can included on report. My downstairs portion is 3/4. It has separate entrance but appraisers don't count it.