I think as others have been speculating, the retail channels are not stocking the Z68's yet because they are trying to squeeze as much as they can out of their P67 inventory first before they bring in the new boards. So don't expect these to be at a brick and mortar store for another 2-3 weeks.
I blaim the recall for this. Instead of the 5-6 months to sell these boards before the Z68 came out, the reality was they have only had them for 1 month, and they most likely bought batch sizes based on a 2-3 month inventory stock, which they have now been saddled with due to so many people who might have upgraded simply holding off until the Z68 came out (since it was such a short time frame between when the fixed P67 hit the market and when the Z68's were officially released), so that slowed sales down even more. So instead of putting a new product on the shelves which is priced within $10-20 and would canabalize the sales of a product they already paid for and have in inventory, they are simply waiting until their P67 stockpile goes down as much as they can, feigning that they have "never head of the Z68".
Which is why there is this great thing call internet sales....