I have been told that Hitec 475BB on 6 volts is a pretty good cheap servo. I am planning a .60 size 3D plane build and will be using a mix of Hitec 425BB and 475BB powered by a nimh 1450 @ 6V battery pack. These servos can be found for less than $15.00 each. If you want to step up to a little faster and more power Futaba 3010 and JR 821's are fairly strong and fast but around $30.00 a piece.