Same with .hack. They are just popular so there is/was a high demand.
So yeah the JP Premium Box for Mana Khemia definitely appears to be the same, so that leaves me with the first Neptunia w/ the playing cards. Only 1,000 of those released in the good old USA as well. I think Mana Khemia 2 online store only one was 2,000 copies. I wish they would just specify for everything.