Here you go.
http://www.gameofjapan.com/product_info.php?products_id=2488
This seems like a pretty awesome site. How many of you guys have ordered from here?
I've only ordered from it once, so I only have very limited experience with them.
I bought my Duo from there and they shipped it from Hokkaido so it took some extra time for it to leave Japan. They also sent me Galaxy Fraulein Yuna 2 instead of the first game - I double checked my order because of this. The box was a bit roughed up but that's not their fault, inside things were wrapped pretty good.
The fact that I got the wrong game doesn't bother me that much, as I have the first Yuna for Saturn (and it seems to be quite common) so I'm thinking I could try them again.
Also, the Arcade Duo card is available from Japan Game Stock for just under the price of Game of Japan:
http://www.japangamestock.com/buy_video_games.php?products_id=3156I've ordered a controller from them before and it went well, they also have good prices for consoles/systems in my opinion.