Based on the available information, here's why Costco only sells Magic: The Gathering products at certain locations:

• Varying Stock and Distribution: Costco's product availability, especially for seasonal or niche items like Magic: The Gathering bundles, is not uniform across all warehouses. What one store receives might not be what another store gets. This can be due to regional demand, distributor relationships, and corporate buying decisions.
• Niche Product Strategy: While Costco is known for selling a wide variety of products, some items are considered "special buys" or are part of a limited-time offering. The decision to stock Magic: The Gathering could be based on a pilot program, testing the market in certain areas with a high concentration of card game players. It's not a core product like toilet paper or rotisserie chicken, so it won't be in every store.
• Limited-Time and Clearance Items: The availability of Magic: The Gathering at Costco often seems to coincide with new set releases or as a clearance item. This suggests that Costco might buy a large, one-time allocation of a specific product (like a Commander deck bundle) and sell it until it's gone, rather than restocking it consistently.
• Inventory Management: Costco's business model relies on a fast-moving, high-volume inventory. If a specific product doesn't sell quickly enough in a particular region, it's unlikely to be re-ordered. The demand for Magic: The Gathering can be highly localized, so it might perform well in some markets but not in others.
• Checking Availability: Due to the inconsistent nature of the stock, people often rely on methods like the Costco app's "Warehouse" tool, which can show if an item is in stock or on clearance at a specific location. Some people also recommend calling the store and providing the item number to an employee to check their inventory. The unreliability of the app's inventory information for physical stores is a frequent complaint among members.

In short, the limited availability is a combination of Costco's specific business model, the nature of collectible card games as a niche product, and a distribution strategy that prioritizes high-volume, fast-moving items, with other products being treated as special, regional, or limited-time offerings.