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