Here in Japan, you can get one Sony Dual Layer media disk if you purchase the Sony dual layer DVD recorder. No store yet has dual layer media over here (As of 15 Aug 04). Phillips and Matsua (Panasonic) have released Blue Laser Dual Layer Media according to the press release, but I have yet to see those products in the store yet.
The price was 3,500 JPY (US $32) for a Single Layer Blue Laser Disk (25GB). 7,000 JPY (US $64) for a Dual Layer Blue Laser Disk (50GB).