6V is not good for the Arduino which is why I said you could carry on using the 9V 2A supply for JUST the Arduino and any sensors you have.
The alternative is to get a 5V 5A power supply which will run the servos AND the Arduino (you connect it to the 5V pin NOT the barrel connector). The catch with that is the servos will not have quite as much speed or power as they do on a higher voltage.
Steve