Booster Packs

Single packs, for when you want to rip a few without buying a whole box. Each one is a random handful of cards from one set, so it's a cheap way to try a set, add to a deck, or chase a card.

There are Play Boosters from a run of recent Magic: The Gathering sets, and packs from the One Piece Card Game and Pokémon. Some packs are sold in store only, and the product page says so.

Opening a lot of one set? A booster box is the cheaper way per pack.