The DIY kit I linked to included a case and power supply, but no monitor.
The SnB CPUs best even the Phenom II X6s and Bulldozer 8 cores. Even the lowly Core i3 21xx outperform the X6s, so you're statement doesn't stand up. TOR isn't going to make much use of a 6 core system to begin with, and going with a CPU thats 1)obsolete, and 2)was outperformed its entire market life, and 3)a CPU that gets beaten by a low end CPU isn't a good buy.
I also disagree with the choice of an SSD. Load times will be decreased, but once the game is started, its irrelevant. At least, that's been the case with all games up to this point. And with TOR allegedly taking 40GB, and Windows 7 taking ~15GB, you're going to need to spend much more on storage than you would with a traditional hard drive. You'll get more bang for the money with a better video card and CPU than an SSD. And I'd expect that there will be many expansions, DLC, and patches for TOR that WILL eat up more space.
To the OP, building a PC from scratch isn't difficult at all, so long as you can follow simple instructions and match up a shape to a hole.
But, I would wait until AFTER the game officially ships before making any purchases. You always want to know how hardware performs on a title before you spend money on hardware. Put off buying new parts until Christmas or New Years, the game will be out by then and you could potentially take advantage of holiday sales.