Check out this site http://www.marijuanagardening.com/marijuana_crop_galleries.htm It uses 2-400w MH lamps....system can hold 168 plants but used 84 and got 3 lbs off of it...pretty tempting to order this system but the price is $3,000 USD
that doesn't sound like a good return on the yield. 3 lbs from 84 plants, doesn't seem worth the effort.