Check eBay and search under garage lighting, then 10w, 20w, 30w "cool white" under LED lighting. You can find waterproof, outdoor, LED floodlights for under a $100 for TEN of them! Those however are 10w putting out 800~900 lumens. The 30w units will put out 2700~3000 lumens! (And they are only around $250 for 10 of them.)
That's half what you'll pay for a 6 bulb HO 48" tube fluorescent fixture.