REI offers the Katadyn BeFree 0.6-Liter Water Bottle and Filter Set for $19.89. (Amazon charges the same with free shipping for Prime members, however it won't be in-stock until December 3.) Opt for in-store pickup to dodge to the $5.99 shipping charge. That's the lowest price we could find by $20. It features a filtered tip with an EZ-clean membrane. Deal ends December 4.