I've been looking all over the web for a separate battery magazine for the 5D3 grip, to hold extra LP-E6 batteries, for quick changing. I found that the part in question is called the BGM-E11L (the BGM-E11A is the AA-holding variety) but I can't find it on sale anywhere. For instance, the 5D2 magazine, the BGM-E6, can simply be bought at B&H.
Do I need to find a service center for parts like this? Does it usually take a few years before Canon puts 'em on sale? Are they for CPS peeps only? Do I have the wrong type number? And if all else fails: does anyone know of an aftermarket grip with identical magazines?
Thanks in advance for your esteemed input