I was recently in the same situation as you! I was buying a computer for this game and was completely lost.

I bought an x51 from Alienware (despite people's negative reviews around here on Alienware.) It's GREAT. It handles this game easily, 40-60 FPS even in the most congested areas.

For 999.99 I got an i7 4770k, GTI660, and 8 GB RAM. I was having a hard time finding a similar deal on stuff even custom built. I recommend you check it out. They have daily sales from time to time. The only downside is you have to wait awhile for it to get to you but I couldnt be happier with it.