Are you sure it is improtable to the U.S.?
I was able to successfully purchase the Zombie Bait Edition earlier this week but I get the following error with the AC Skull Edition:
This item cannot be shipped to the address you selected. (Learn more.) You may either change the shipping address or remove the item by clicking Delete.
I was able to yesterday when I posted it. I am sure that come closer to release it will be importable again. Just like Injustice took a while etc,etc...