6 Apaches or 6 a51 will cover a 4x8. I'm guessing your area will be an 8 x 8. So probably 10- 12 of either. Maybe 8 panels if you use light movers.
10 to 12 Apache's will cost you between 8-13 k depending on their bartering policies at apache. And unless I see people getting more than 1g a watt from a unit like that, i wont pay 7$ a watt because its just a bit much for any light, think about it.... Once you include water ,electricity, nutes(if u use them)medium, systems, tents, Etc... for one of those lights to be profitable in a grow scenario, my rule of thumb is that the light must pay for itself atleast on every run. So yeah if you can get 160 -180gs off that Apache tech then I'd say its well worth the 1099 or whatever you work out, that's looking like some money made on the light, but if your closer to the 80 to 120 area, you aren't even breaking even on the light, minus everything else!! The only way id Get those lights is if I had capitol to purchase 10 -12 or more of them, and id only do it if they made me an incredible offer, allowing my minimum harvest to go down significantly.
I guess I didn't take into account those who just grow for themselves, but honestly no one Ever used 12 Apache's to grow their own medical stash, without parting some of that off for reimbursment, or donations, or whatever you want to say. Just saying as most people on here are normal folks IE: poor/middle class without 10s of thousands of dollars to spend on lighting it makes more sense to give them advice on good to ok lights that are More reasonably priced, Like Blackstar, cidly(apollo), eshine(Manufacturer of Advanced LED), California Lightworks=good choice, Area 51=good choice as you said, The HANS panel and many others that are developing as we speak. These are much better choices for people who do not have money for APACHE/LUMIGROW.....Because im pretty sure that everyone would have those lights in their grow journals/rooms if they could afford them. I wont lie tho I'm set on getting 2 of the Lumigrow 650s ES after a few harvests those things look fucking solid! and still at about 3 $ a watt, its more affordable than Apache at 7$ a watt considering That 4 Apaches wouldn't out perform 1 lumigrow 650 es by enough to make the price paid worth it. 4 Apaches = 600 -620 watts at the plug roughly, 1 Lumigrow 650 es=600-650 watts/ 4 Apaches = $4000/ 1Lumigrow 650= $1600, the results here are pretty obvious.....
At the end of the day, its all opinion anyways. If you have the money, then should do whatever you want... Good luck with your lighting quest!!! took me roughlly a month to decide on a company/light but i also researched every day until i just couldnt any more. So yeah Id say if you were still choosing between the area 51 and apache, Area 51 is an easy choice as their warranty is unbeatable, and their product is awesome, at a reasonable price. Once again Good luck and godspeed!