Starting November 24th the Microsoft store (both US and Canada) are going to have a buy one - get one free deal going on. More specifically if you buy a 950 XL, you get a 950 and a display dock for free.
In the US the 950 XL is 499 so
Update: Now available to preorder from MobileFun.com and MobileFun.co.uk. The price for either cover is $48.49 (USD) or £57.99 (UK).
Mozo Accessories has posted a teaser image of an upcoming cover for the Lumia 950 and 950 XL that will be made of real wood on Facebook.
These are not yet available