same problem i was faceing... i was gonna to use 2-4ft t-5's giving off 5200lumens a peice, but because of location promblems had to switch to CFL's... priced it out and serval smaller 24watt 1600lumen and 42-watt 2400lumen CFLs are alot cheaper per lumen than one single large 100 or 150 watt.... but havent tried it out yet, so ill let u know how it goes....