Walmart offers the Thermos Foogo Vacuum Insulated Stainless Steel 10-oz. Straw Bottle in Pink/Purple, model no. BS535PKW3, for $8.99. (Amazon charges the same in Pink/Purple or Watermelon/Green, model no. BS5354WG3, with free shipping for Prime members.) Choose in-store pickup to avoid the $5.99 shipping fee. That's the lowest total price we could find by $4. It purports to keep liquids cold and fresh for up to 10 hours.