wow, that light is pretty sick. i use just 2 and my plants loved it, very healthy and strong. your right though, after a foot they stopped growing. i added a shit load of 46 wtt (100 equivalant) CFLs suspended in the canopy. 8 must be nice.Here is another site, It is not the commercial type but it is only $200
http://www.plantlightinghydroponics.com/hydrofarm-lamp-3k65k-t5-fluorescent-grow-light-p-2484.html