For a cheaper servo i would say these are good from what i hear.
In all honesty if i was you... I would get this set of combo, I'd buy a ESC, Motor, And servo all seperate
ESC
www.hobbypartz.com/07e-c-xerun-150a-sd.html
Motor
www.hobbypartz.com/96m801-4074-2000kv.html
Servo
www.hobbypartz.com/33p-solarservo-d770.html