The most expensive part is the lighting, everything else costs very little. And by expensive I mean relative to the other equipment for the build.
$20 each for the light fixture+reflector. Maybe $20 for everything else(PVC, screen).
I installed one about 5 weeks ago, POD growth exploded and although I haven't seen significant nutrient decreases yet, the screen continues to mature each week. I suspect within a few more weeks I will see my N and P start to come down.
As for the new design, there are a lot of kinks to work out in my opinion, and the waterfall design is actually easier(again in my opinion).
Here is a video to show the crazy amount of PODS as well as the ATS running.
http://www.youtube.com/embed/_Z1Pr8dWurQ