Check out why this PC build is (currently) state-of-the-art.
The cheapest model starts at $3k+, while the highest at $6k+. These are probably going to be for those high-end gamers who just need to have the latest and greatest. Must be nice to spend that kind of dough on a PC. I guess you get what you pay for.
PS. Curse.com is currently having a contest till March 16, 2009. Enter to win a Reactor here.