I was at a conferance about five years ago and there was a presentation on Plasma lighting for commercial and industrial use. I thought at the time that there were possabilities for the reef tank, but the cost was way too high!
These Plasmlyte units have a good spec, but I think that they are still a bit over priced.
There is a move within the industrial arena to the use of Plasma fittings, as this grows the cost of lamp production will fall. But like all things related to our hobby a healthy premium is added to what you would pay for a simmilar device made for other market uses.
At one time LED's were thought to be expensive, and to a degree they still are, but they are now main stream.