If you got the individual pieces yourself or 3D printed it can be much cheaper.
The main electrical components are:
1 x Arduino Uno (I used the modified Uno called "Orion" that has RJ2 ports) 2 x Stepper motors 1 x Servo motor 4 x microswitches as limit switches 2 x stepper motor drivers (they handle the microstepping) 3 x RJ25 breakout boards (for connecting the limit switches to RJ25 ports)
This was a prototype to prove the concept. I'm going to experiment with 3D printed parts next in a new design.
If you're feeding in coordinates as Gcode I would recommend loading Grbl. Keep in mind Grbl has specific pin requirements that make it incompatible with the Orion's RJ25 ports, so you'd have to wire a normal Arduino. Makeblock supplies Gcode firmware that works with the Orion.
For the demo in the video, the firmware was custom to handle real-time input and recording of motion.
On the host computer side, it was just a python script that interfaced with the Wacom tablet. Specifically: https://bitbucket.org/AnomalousUnderdog/pythonmactabletlib
I also hacked support for the Myo armband and mouse support.