Also consider that you can use servos that are designed for continuous rotation as long as they comply with the max speed and torque specs in the manual. Not exactly high power output (Power = torque * rotational speed =100 rpm * 55 oz-in = 10.5 rad/sec * 0.39 Nm = 4.1 Watts) but it could be useful work.
http://www.acroname.com/robotics/par...-RO-SERVO.html
The above servo MAY be sufficient (I didn't find it's max speed at 6V spec).
This has not been made really clear to teams yet but if you use servos other than a Hitec HS-322HD or Vex servo, your inspector will probably ask to see a datasheet for confirming max speed and torque. Please bring datasheets or at least load them onto a computer for inspectors to check.
Russ