Several years ago when looking for cheap servos to use for my walking robot I purchased a handful of HXT900 micro servos from HobbyKing. They seemed like an incredible deal for less than $3 each, but after brief experimenting I gave up on them. They were very jittery, not terribly strong, and when run at 6V the motor would burn out quickly if the output was stalled. I tossed them in the junk box and forgot about them, writing them off as not usable for my robots.