If you're looking for Yu-Ggi-Oh cards, here are a few possible places to buy them online:
Pokeorder carries a wide variety of Yu-Ggi-Oh Single Cards, Booster Packs, and Theme Decks.
CrossToy has a more modest collection available, but offers Yu-Ggi-Oh booster boxes for sale, which are much cheaper than buying the boosters individually.
Or, check eBay for Yu-Ggi-Oh:
Yu-Ggi-Oh Video/DVD
Amazon is a good place to find Yu-Ggi-Oh videos and DVDs or even books and computer games:
