REI offers the Hydro Flask Standard Mouth 18-oz. Vacuum Water Bottle in several colors (Black pictured) for $12.93. Opt for in-store pickup to avoid the $5.99 shipping charge. That's $3 under our mention from last August, the lowest price we could find by $17, and the best we've seen. It features double-wall vacuum insulation and keeps contents hot for 6 hours or cold for 24 hours.