They're willing to pay big bucks for an 80 amp charger (so it charges faster, but you still have to plug it in), so I would guess a couple thousand should cover it. Lemme see: 3 servo motors and a charge port detection system. Might not even look like the snake. Might just be a box with a charge probe. My model would be cheaper than the snake, but the snake would be what everyone wants, and the snake comes with the Tesla emblem.
Problem is, I suspect they are busy with AP software, ramping up the X, getting ready for the 3 reveal, getting powerwalls out of the Gigafactory, building new supercharger sites so Texas doesn't secede, etc., etc., etc.
So, there might be a wait.