http://store.steampowered.com/universe "This November, we're bringing everything that makes the PC great—the best games, the biggest communities, and the most exciting technologies—to new destinations." What do you want first and why?
There are many versions of the steam machine from different companies and not just alienware. They were just showing that specific one. If you look here: http://store.steampowered.com/sale/steam_machines you can see the various machines and their pricing.