What computer should I get if I want to run Arma3 perfectly, that isent custom built

Solution
Well there really is nothing that you can find at bestbuy or Depot that will run it perfectly, or even well for that matter. Ordering one online is still going to be an issue, as most prebuilts are lacking in the performance area. I would Highly recommend building your own if you want perfect performance, if you have to have prebuilt go to newegg and most likely lower your standards.
 

Zero_

Distinguished
Something decent I found. While not the fastest for the price, It is sort of balanced. Sort of.

CyberpowerPC Stealth Rogue GXi1200A - $799 http://www.amazon.com/gp/product/B00CSJITZO/ref=as_li_qf_sp_asin_il_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=B00CSJITZO&linkCode=as2&tag=banforbucga08-20


And something with a GTX660 for a bit more.

CyberpowerPC Stealth Ronin GXi1400A - $899 http://www.amazon.com/gp/product/B00CSJIU08/ref=as_li_qf_sp_asin_il_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=B00CSJIU08&linkCode=as2&tag=banforbucga08-20
 
Solution
If you don't want to build it yourself, you only have two options:
1. As stated above, go to a local computer store, pick out the parts, and pay them to build it for you.
2. Go to a custom computer website like ibuypower.com or cyberpowerpc.com and order a custom built pc.

Of course, building your own is a much better option.

As far as I'm aware, there's no prebuilt pc that actually have a good graphics card without being stupidly overpriced.