Kensington PowerLift iPhone 4, 3GS, 3G Back-Up Battery, Dock and Stand for $19.99 Shipped

Kensington PowerLift iPhone 4, 3GS, 3G Back-Up Battery, Dock and Stand for $19.99 shipped after this $15 rebate.  Here is a screenshot for your reference.  It features a kickstand, 1200 mAh charge, built-in dock connector, LED battery indicator, and more.  Most places have the Kensington Powerlift back-up battery, dock, and stand for about $29.