Bodyworks,
I got the control horns at Tower Hobbies. The aileron horns are Great Planes, Tower #LXEVC9 and the elevators are Dubro are Tower # LXEMF9. I did have to cut length, sand and drill holes in the elevator horns to get them to line up over the hinge line. I other words they were about 4mm too long. The only drawback is you can't get them individually, you have to purchase them with all the hardware. I thought it was worth it because of the clean application, and I got the plane on sale. If I were to build another one I would consider the Great Planes for all control surfaces. They are less expensive and though they might not get clevis pin directly over hinge line it would probably be enough to achieve Ackerman effect.
Greg