You cannot power the servos straight from the arduino, it will damage the arduino. What you could do is get 5 volt regulator, and a diode. If you put a diode from the GND pin on the regulator and then to GND, it will increase the output to about 5.3V.
Now a regular 9V will last for about a half hour, due to a lack of sufficient current. Try a 9.6V or 7.2V battery pack.