The nova rossi .21 BF Or something like that. it's as low as $160 in some places. It's seriously under rated. It produces alot more power than it claims, I use it in my Jammin X1CRT.
I think there is a Hitec servo that has 133 OZ of torque at .20 speed for about $40 dollars! the name escapes me at the moment, it's there ultra torque servo!