I will wild-ass-guess and say 300 watts, which would cost you about $1500.

www.LEDwholesalers.com

In 70 watt increments, I think the blue in the center with 7 reds on the outside for $45 (fixture) + $33 x 6 + 35 = 45 + 231 = $273 for 10 x 7 = 70 watts or $3.90 per watt

If you do the 15 watt bulbs it's $45 + 62 * 6 + 67 = $484 for 15 x 7 = 105 watts or $4.60 per watt

If you do the Procyon 100, is $549 from indoor agriculture for 100 watts or $5.50 per watt.

Buy LED Grow Lights, Procyon 100
Procyon-100 100W LED Grow Light - HomeGrownLights.com

So basically you're going to pay $3 to $5 per watt for LED and you need about 1/3 as much wattage. Someone is going to correct me here, but that's okay, I'm doing the best I can to answer the question.

People selling the LED lights are going to say you need less than 1/3 the wattage, but I think if you go to 1/4 the wattage or less, you're going to be disappointed.

This is my BEST GUESS so please be easy on me if my numbers are wrong. I did a lot of crunching before pulling the trigger on the Procyon and more importantly seeing the results of other growers on this forum indicating it does in fact work.

Also, you can get these bulbs cheaper that this too if you scrounge, but I figured I would just pay full price since I only need 100 watts, the most I could save is probably $150 or so, and if I was price conscious, I wouldn't be doing LED to begin with.