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