I bet you could build one for a lot cheaper than its offered. I guess the only benefit ofnthisnsystem is that the light hits the plants at a more natural angle and would eliminate the one sided bud growth that you see in a vertical setup.
I bet you could build a wooden "cylinder" and rig up a motor on a timer. You may be able to use a spinning Christmas tree display stand to turn it slowly.
Its an interesting setup, but it seems like it requires a bunch of expensive components when compared to a vertical setup.