Here are some Robotis part websites that are relevant to this kit. More to come!
Servo motors: Robotis Dynamixel AX-12 or AX-18 smart servos for larger robots, Robotis XL-320 smart servos
for smaller robots. Alternatively, high performance hobby servos, modified for continuous rotation as necessary.
Low level controller: Arduino Uno, Micro or alternative Arduino-compatible microcontroller such as the Robotis OpenCM904