True, but the Japanese version also had voice acting and lyrics for the songs, all of which were removed for the NA release so I believe there was no need for it to be on a dual-layer...
As far as the game itself, I'm playing it right now and enjoying it. Given its release timeframe, it is very dated, but it's still fun in its own right and the music still kicks ass. As for deals, I snagged my copy from Overstock back in March during their 15% off sale, but given the seemingly limited release quantities it had, you may have to wait for it to show up on the used racks to get a decent price for it...