The Costco coupon book strategy 2026 — formally titled the Member-Only Savings booklet and arriving in members' mailboxes approximately once per month with valid savings windows of 28 days — is one of the most commercially underappreciated dimensions of the Costco member experience. Most brands that study the Costco channel focus intensely on membership fees, buyer evaluation criteria, roadshow execution, and digital strategy. Far fewer have analyzed what the monthly coupon b