Amazon offers Prime members the LifeStraw Personal Water Filter for $13.90 with free shipping. That's cents under our September mention and the lowest price we could find by a buck; many stores charge at least $20. This award-winning, BPA-free device enables you to safely drink contaminated water. It removes almost 100% of waterborne bacteria and protozoan parasites and will filter up to 1,000 liters of water.