Instructions
Purchase a new bag from vendors you find throughout the game. Some backpacks can only be purchased at specific areas in the game, so your opportunities for newer, larger bags will increase as you level up. You must have a high level character to survive in certain areas of "World of Warcraft." You can't take a Level 1 character to Blasted Lands to find a Traveler's Backpack, for example, so continue exploring as you level up to find new bags.
Visit the Auction House in the Trade District of Stormwind to bid on backpacks. Players often sell the goods they collect while on raids or quests at the Auction House, so check regularly to see if you can find a decent backpack. Remember that Auction House prices are generally higher than you would pay if you purchased the item from a vendor, so be prepared to shell out some gold for a good bag.
Complete quests to find backpacks on creatures. When you kill an enemy in "World of Warcraft," you have the opportunity to loot the creature's corpse. Right-click to see what the character has and left-click to take its items. Alternatively, you can click "Shift" and left click to auto-loot the creature. You can often find rare or unusual bags on corpses throughout the game.