I wanted to build a sub 650-700 gaming machine for 2013-14 mmos (Like Tera and Blade and Soul). Did my research on this one. I worked out my OS (win7), keyboard, monitor, speakers, mic, and mouse separately. Along with an office chair and a table everything was around $950.
CPU : I'm fine with a duo core i3 since it doesn't bottleneck the R9 270.
Motherboard: Cheap, USB 3.0s and of course 1155 for the i3.
Memory : This was on a small percentage off and I grabbed it. I didn't really wait on a deal for this one.
Storage : Grabbed the samsung evo for $91, I'll get a HDD later.
GPU : It's like the old 7870 from what I've heard so I grabbed one at $180.
Case : Good space, nice red color, and cheap.
PSU : 500W Corsair, I trust it. Nothing has happened a month in.
ODrive: Cheap so I can install my OS + Burn my CDs etc.