Did you check the front page of TomsHardware.com? There is a nice scrolling banner there with Gamign Rigs for $500, 1000, 2000, etc.
As for the 'extras' yes they are important to the make up of it, because if your going 6Plex Video display determines the type of video cards your limited to and the type of CPU, as well as power needed for it is all custom and much more expensive, and more technical. Storage media also matters, because if money is no object then buying a 512GB SSD and a 10,000RPM 2TB HDD again is UNIQUE and specific solution, but might be better solutioned with a RAID 5 configuration of (6) 512GB SSDs that would narrow down whom you would buy from, but you would have 'the best gaming PC'.
MaximumPC often shows what is the best of the best, as shown in last year best computer ever (http://www.maximumpc.com/article/hardware/dream_machine_2012_future_now) for only $14K