South Cobb average prices have gone down quite a bit in the last 18 months. There has been a definate downtrend in prices. The number of homes selling have also dropped.
This is a large market area that goes from the Perimeter in Smyrna west to the Paulding county border. It includes Mableton, Powder Springs and Austell. One needs to be careful about using these stats to make a general evaluation for the entire area.
Average number of days on the market spiked up to 151 and sales to original list price ratio has gone down to around 85%.
The numbers below are for single family detached homes in FMLS area 72. Links to stats for other areas are at the bottom of the page.
Year over year, total transactions decreased from 97 to 81 (-16%)
Year over year, average sales price decreased from $234,167 to $196,788 (-16%)
All data for graphs is taken from the FMLS statistics put out by Smart Numbers.

For other market areas as shown in the following map, please click on the links below.

All areas combined: Summary of all FMLS areas
Area 13: North Fulton, Alpharetta/Roswell West of 400
Area 14: North Fulton, Alpharetta East of 400
Area 131: Sandy Springs North of 285
Area 132: Sandy Springs Southe of 285
Area 21: Buckhead
Area 23: Midtown/Virginia Highlands
Area 31: South Fulton, West End
Area 33: South Fulton outside 285
Area 81: East Cobb, North
Area 82: East Cobb, Central
Area 83: East Cobb South
Area 72: South Cobb
Area 73: Cobb West Central
Area 74: Cobb West
Area 75: Cobb Northwest
Area 121: North DeKalb, Dunwoody
Area 41: DeKalb, Tucker
Area 42: DeKalb, Stone Mountain
Area 43: DeKalb South
Area 221: Forsyth East
Area 222: Forsyth Southwest
Area 62: Gwinnett, Duluth/Buford
Area 64: Gwinnett, Southwest
Area 161: Clayton County