It comes out Q4 this year so the prices should go down and MS probably got some parts for a lower rpice so it could possible be $50-500.
You need an 8GB GPU as that's the amount available to games on Scorpio.
RX480 8GB GDDR5 is $245 or $60 extra, so $620 atm.
The first 4K UHD drives are out in Japan now, can't find a retailer price though, $270 on EBay
Plus a controller, hdmi cable, headset, packaging, OS
They made up for the 12GB GDDR5 with the 12GB DDR3, so not really much price difference. The 4k BD drive would be more, but if they use the same drive between the XB1S and Scorpio, that will save them a lot with mass production, so maybe $100, $150 tops instead of $270. Plus all the accessories correct.
It puts you closer to the $600 mark anyway. They should be able to do it for close to $500 with mass production and direct purchasing. The mass production for Scorpio won't be anywhere near the XB1S numbers though, so $499 is a pretty good prediction for a retail price without taking much of a loss.