I have a 5 acre farm for sale w/ a 6000 sf house, pasture, arena, 6 stall barn, trails on a gorgeous gravel road w/ all horse farms in Crabapple. You can see it @ http://web.mac.com/art2ride1. I would consider a lease/ purchase under the right conditions.
There are only 2 that I know of, though neither has 4 stalls. I'm sure you could add on to the one at least. There may be a few out there that are for sale including one in Cherokee county with a 6 stall barn. The link below shows the 2 rentals.
Good evening and you are in luck. I am your guy for the horse market in the Alpharetta/Milton/Roswell/Cherokee area. I would also suggest keeping the area of crabbapple in your sights as there are many properties around in this area as well as the other ones you mentioned and property in this area. Please contact me to discuss how i can assist you with your search. Thanks.