Pawn shop, if possible. Gun shop. Look for a very used Smith & Wesson, Colt, Ruger, Taurus, High Standard revolver.
Know the specs you want: barrel length, sights, mostly. The looks aren't material if the weapon is sound.
Learn about lockup on a revolver and the timing. Not really involved just knowledge. The handling to determine the tightness of a revolver is pretty simple. If I think a very used revolver is tight and in time, I will still put a wooden pencil ( eraser down) in the barrel and dry fire to see the pencil pop up out of the barrel. Learn some about what a bore should look like and be viable.
A nice gun shop/ pawn should help and show how this is done. Ask nicely. Listen. Don't know too much. If they won't help, walk.
A good old tight revolver is as good or better than a current production one.
Luck. A trusty revolver is worth more than your third hard drive backup.