Touch Cover is the flat surface touch QWERTY that docks to the tablet and doubles as a protective cover. If you wanted a different color, the price would rise to $618.99 ($499.99 for the tablet plus $119 for the non-black Touch Cover.
Here's where Costco earns its reputation price wise. It is offering every possible SKU available with the 32GB model and the Touch Cover for $599 or less (the cyan or black versions are $589). Move up to the 64GB Microsoft Surface table with any color Touch Cover for $699.99 while cyan and black are $679.
Costco is selling the Type Cover for $119.99. This is the cover that offers a more traditional style of QWERTY keyboard with raised keys, which also doubles as a protective color. The Type Cover is $10 more at the Microsoft Store. So while it might not seem like a lot of money, look at this way. Why spend more for something that you can buy cheaper from Costco, especially if you are already a member?
source: Costco via WPCentral