The Costco shopping mistakes guide 2026 covers the specific errors that even experienced Costco members make — the decisions that feel like savings in the warehouse aisle but register as financial losses when the expired spice jar gets thrown away, the duplicate membership renewal processes, or the credit card cash back that was never earned. Shopping at Costco can be extremely rewarding if done correctly. However, common mistakes such as impulse buying, ignoring unit prices,

Costco sells gift cards to some of your favorite places at a discount — and it's one of the most underutilized financial strategies available to any Costco member. The gift card arbitrage system is not a coupon hack, a promotional trick, or a limited-time opportunity. It is a permanent, structural feature of the Costco membership — available every day, year-round, through Costco.com — that allows members to effectively pay 75 to 85 cents for every dollar they spend at partici