To be honest I'm not sure but I have asked Gigabyte the question.
For the UD5 & UD7 I guess they will be around the £150 - £180 mark based on cost of similar 8 series boards but, as I say, this is just a guess.
Still, on the bright side, once they hit the shelves we will all know how much they cost and until then we can just dream about owning one!