Botach offers the Aquamira 22-oz. Water Bottle with Microbiological Filter, model no. 41210, for $19.95 with free shipping. That's $2 under the lowest total price we could find elsewhere. The bottle features a dust cap, finger loop, and an activated-carbon filter which treats up to 100 gallons of water and removes a purported 99.9% of Cryptosporidium and Giardia.