REI Garage offers the CamelBak 21-oz. Podium Chill Insulated Water Bottle in Eucalyptus or Sprint Green for $5.73. Opt for in-store pickup to avoid the $5.99 shipping charge. (Amazon charges the same via its add-on program.) That's the lowest price we could find by $4. It features a wide-mouth opening and double-wall insulation.