Amazon.com : Neewer Vertical Multi-Power Battery Grip(replacement for Canon BG-E13) for Canon EOS 6D, uses one or two LP-E6 battery packs or six AA Batteries(Batteries NOT included) : Digital Camera Battery Grips :
Used Canon BG-E13 Battery Grip | MPB
Canon BG-E13 Battery Grip For Canon EOS 6D Camera - Lenses and Cameras
Green Extreme BG-E13 Battery Grip for Canon EOS 6D DSLR Camera - Walmart.com