Trader Joe’s is different than other grocery stores in America. Unlike supermarkets and big-box chains like Costco, Trader Joe’s relies on private, international sources for its eclectic mix of products. On top of this, all its branding is done in house — giving all of the store’s offerings a quirky, vintage feel. Yet, despite the supposedly good deals, people always end up spending more than they expect when they visit the Trader. Why is this?