Walmart offers the PUR Advanced Faucet Water Filter in Chrome, model no. FM-3700B, for $23.91. (Amazon has it for the same with free shipping for Prime members.) Opt for in-store pickup to avoid the $5.97 shipping charge. That's the lowest price we could find by $6. It features a 360-degree swivel and LED filter life indicator. Each filter provides up to 100 gallons of clean water.

Update: The Walmart item is no longer available; however, Amazon still offers it for$23.91 with free shipping for Prime members.

Update: The offer at Walmart is now available.