Cactus Music
NCIX is Canadian by the way, not sure if they ship across the border. But they have always has the best prices for me, and mostly free shipping deals. Things change when the border gets in the way.

I contacted NCIX for some info when I was shopping around for the parts to build the system in my sig (all in a huge Fractal Design Define XL case).  Without my suggesting anything, the representative asked me for a list of what I needed and said he'd see what he could do.  I'd already pretty much decided to get most of my parts from them so I was happily surprised when his price was 200$ off the total.  You can't get much better than that.
 

Not only that, the user forum is real helpful. Got a geek question? they answer pretty quickly. Excellent forum just like here. 
For a small fee they will build and test your rig too.