Buy.com offers the Kensington Charging Dock with Mini Battery Pack for Apple iPod / iPhone, model no. K39265US, for $23.99. With free shipping, that’s $6 under our January mention (which included a rebate) and the lowest total price we could find by $11. This dock simultaneously charges your iPhone or iPod and mini battery pack. The battery pack allows up to 30 hours of music, 6 hours of video, and 3 hours of talk time.