The admin has been involved, for over a year now. It's just never been made public. (And honestly, was never meant to be public, but oh well.)
Anyway, back on topic...
The Servo Recorder/Playback unit is a very interesting idea, but at $110 for 4 channels, that yields just two X/Y pairs. That's pretty close to what a sound card DAC would cost. Also, to "program" the unit, you would need to twiddle the knobs in real-time to record the movements. That could get difficult if you wanted circular motion. (Ever try to rotate two knobs in a sine-wave pattern while one is 90 degrees out of phase with the other?)
Another suggestion was the Adafruit 16-channel servo driver. This unit is only $15, and if I read the spec sheet correctly, it allows for 16 separate PWM outputs. Also, it appears to be able to drive smaller RC hobby servos directly. (Not sure if the gear-driven ones would require more current than this thing could supply though - we'd need to look into that further.) The real issue though is that it receives all it's data over a 2-wire connection from a controller like an Arduino or a Raspberry Pi. So now you need to program all that I/O in the Arduino.
I have never worked with the Arduino, so I'm not sure how simple this would be. I would think that for someone with a programming background it wouldn't be too difficult, but I'll reserve final judgement on that for someone with more experience.
Still, if the Arduino (or the Raspberry Pi) can be programmed easily, then using the Adafruit board would seem to be the cheapest solution. You can get a pair of small RC servos for $10, and building a mount out of sheet metal (or even wood, in a pinch) can't be all that expensive.
What are other people's thoughts? Has anyone here driven a servo pair (or several sets of servos) using an Arduino? If so, how hard was the programming?
Adam