The guy who started clean roots is an awesome grower by the way, and he spent a good amount of time with a manufacturing company doing the prototypes and testing, I'd say a year before he actually started selling them. If anyone is hitting the Max Yield show in Boston next month, he'll be there.
He's working now on how to make the legs adjustable to so you can not only have the drainage and airflow, but also be able to help keep the even canopy.
I've watched some twitter grows that have used them, mostly home growers of 4-6 plants. For large grows I agree, the $9 each would get pretty pricey Cubby. I had Hubby build a fake floor in my room that kind of looks like a wood pallet, with plastic on the floor underneath. That keeps my plants lifted and all the drainage goes onto the plastic.