I have seen them individually at Northern Tool and in sets at Harbor Freight. (but you may be nuts anyway) Whether there is enough room to get one of those sockets onto the crank pulley with the radiator in place I do not know...
What are you needing to do? If just to turn the engine I just put it in 4th gear and roll the car. (always forwards! - never turn the engine backwards or the cam belt is likely to skip a few teeth)