It's official now, the Core is $500, or $400 if you buy it with a Razer Blade or Razer Blade Stealth.Looks like the Core might cost $500.
http://techreport.com/news/29858/rumor-razer-core-graphics-dock-will-cost-500-and-ship-in-april
AnandTech said:Razer also notes that this offer is also retroactive for customers whom already purchased a Blade Stealth earlier this year, as the ultrabook and the Core were announced together at CES and the company doesn’t want to penalize early buyers who were intending to grab the Core anyhow.
Looks like there's a new external PCIe connector coming. Might help with external GPUs and external solid-state storage.
http://www.tomshardware.com/news/pcie-4.0-power-speed-express,32525.html