Could you be more specific? What you do mean by "high price?"
In Japan, they're very reasonably priced, for their level of quality. Nylon bags are in the 17,000-25,000 range, ($200-300 at current exchanges) with full leather bags 40-50k yen. The most expensive Porter I've seen was about 60,000 yen, or around $700, and those are ones that would easily be $2500-3000 from a Euro brand (Prada, Gucci, etc.)
I find them (in Japan) to be about the best bang-for-buck you can get; you pay $200-300 for crappy Kenneth Cole garbage...
They are nearly ubiquitous in Japan; currently the "go to" brand for younger japanese guys, in college, for work, etc. Any train ride will find you seeing half a dozen or more Porter bags from their various lines (and they've got DOZENS of lines from nylon backpacks to full leather briefcases.)
As such, the "fortune" you mention may just be various stores trying to capitalize on limited distribution... the same way that those margiela Aids tshirts are really $45 or so yet Barney's and some other places charge $110 for them just because they suck.