I didn't see a previous post on this subject:
 
VAX MIDI Keyboard Controller - Kickstarter
 
Basically, the Infinite Response guys are working on a cheaper design with some interesting technical aspects:
Open source; kitset delivery; modular design; 3D printer prototyping; very hackable...
 
Check out the video - it's a little stilted in delivery but very interesting.
 
I signed up for an 8-octave version but there are many other, cheaper pledge options. 6-octave poly-AT controller for $550? Some of you may be interested...
 
They are very close to meeting their goal.