It looks like if you're selling on ebay you'd try to get $400 but, wow, that seems ridiculous for a Japanese copy of the game. The cheapest one in the recently sold listings is $285 for a real auction but there are several non BIN sales that are approximately $400. Last I looked I remember it going for a bit over $100 but that may have been a long while ago.
If my fancy college-boy book-learnin' is to be believed then I would imagine that the reason the PCE version is so expensive is that the US version's price went through the roof and caused a halo effect. I seem to recall it not being a rare game at all but I definitely could be wrong on that.