I think it's just in the marketing. If NIS does a better job promoting their DVDs, sales could be strong. I mean, the die-hard fans will always seek out the information or have certain sources to get great, breaking news from. (like a particular radio station I listen to online from the West Coast that I won't name because I don't know if I'd break the rules. lol)
I mean I'm not sure yet just how "limited" the Japanese collectors package was, but...it's seriously going for between $400 and $500, new in box only a year after it's release! What's sad is, I'm almost certain if I snag it for $500, and team it up with the DVD releases from NIS...I could sell the combined set for probably about $1,000 if I toss in a baseline PSP3000 in the deal, at next year's Megacon in Orlando.
Collector's items go really high if they're limited or nicely packaged.
The GameS***s around Central Florida (sorry, no GameT**s out this way) sell out very quickly of the "limited edition" PSP games. For example when I picked up the special edition Lunar for my PSP, they only had the pre-orders available, and when I picked mine up, there were people inside asking about getting it but being told that location was sold out of them.
If there was an English version of this game, with the same level of collectibles in the Japanese version...I'd budget out at least $100 to buy it. Then again, I'm a collector who uses online auction sites to buy and sell off things. So, I don't think of it from the perspective of someone who doesn't care about anything but the UMD. lol