Walmart offers the Contigo 20-oz. West Loop Autoseal Mug in Stainless Steel for $12.53. Opt for in-store pickup to drop the price to $9.98. (Amazon charges the same for Prime members.) That's tied with our mention from two weeks ago and the lowest price we could find today by $5. It keeps liquids hot for up to seven hours or cold for up to 18 hours.