I don't see Apple pricing other current products based on colour? What makes you think they will on this one?
A theory saying they MIGHT price them higher. In the SS collection 18 models are shown but only 2 are Space Black (2 of 10 in the Sport). This could be Apple 'presenting' the Space Black (Gray) as 'special' and worthy of a price premium.
This is unlike the iPhone/iPad which presents all colors equally.