I gots and idear. 
I'm not really sure about any of this, it's a probe into the public knowledge to see if this has been done.
I've been thinking a lot about high-wattage CFL growing... The 200w, full spectrum 5000k bulbs cost $57 bucks, and with the rule of thumb of 150w per plant, that's more than plenty of light.

OK, so who payed attention in geometry class? What's one practical use of a parabola? To focus light into a direct beam. a hyperbola? To distribute light evenly. An ellipse? To send all light from one focus to the other.
Using that thought about the ellipse, and a vertical 200w 5000k CFL (or two for a bigger plant?) you should be able to get 100% of your light from your bulb to your plants. Could you make a grow room or box that looks like an ellipse from above? A beautiful drawing to illustrate is attached.
Maybe hang a mylar curtain in an elliptical way(lots of staples?) from the cieling or top of your cabinet and around your vertical light and plant?
I think it would be really cool
and i like the idea of light affordability. 
edit: possible drawback is that ventilation might be a problem, though you could probably just pull air in the bottom and out the top...

I'm not really sure about any of this, it's a probe into the public knowledge to see if this has been done.
I've been thinking a lot about high-wattage CFL growing... The 200w, full spectrum 5000k bulbs cost $57 bucks, and with the rule of thumb of 150w per plant, that's more than plenty of light.

OK, so who payed attention in geometry class? What's one practical use of a parabola? To focus light into a direct beam. a hyperbola? To distribute light evenly. An ellipse? To send all light from one focus to the other.
Using that thought about the ellipse, and a vertical 200w 5000k CFL (or two for a bigger plant?) you should be able to get 100% of your light from your bulb to your plants. Could you make a grow room or box that looks like an ellipse from above? A beautiful drawing to illustrate is attached.
Maybe hang a mylar curtain in an elliptical way(lots of staples?) from the cieling or top of your cabinet and around your vertical light and plant?

I think it would be really cool


edit: possible drawback is that ventilation might be a problem, though you could probably just pull air in the bottom and out the top...