Actually, it says "set", not "box" -- I wouldn't be surprised if they're just offering a package discount if you get all of them (looks like it's priced such that you get the EP for free), like the RCA Living Stereo sets. 4AD explicitly mentions a box set in the context of the Japanese mini-LP covers, which would make more sense.
I wrote them, guess I better just hope they see my email.
Oh, and for anime fans, are you as excited as I am that they're coming out with three Kenji Kawai compilations? Unfortunately, I only see a couple tracks each from GITS, GITS2:I, and Spirited Away (from googling), but at least they have "Reincarnation" (one of my favorite tracks ever).