Some Resources:

http://r2d2-robot-electronics-motors-servos.blogspot.com/

Main Motors

Daleks - use Baldor wheelchair motors.

R2D2/K9 - Use belt drive motor from scooter

Motor Drivers

These look decent, $80 for a 2x12Amp Should drive a K9.

https://www.dimensionengineering.com/products/sabertooth2x12