Might be picking up a used 5d3 later this morning from a local camera store I frequent. They also have the BG E11 grip used for $169. I'm debating whether to pick it up as well.
I found I didn't use mine on my old 7D all that much, only when I wanted extended battery life. My 7d2 is fine without and I'm guessing the battery life is good on the 5d3? I do like the convenience when portrait shooting, but don't know if that would justify the added cost. Perhaps an aftermarket brand would suffice for the minimal use it would get.
Do you think I'd be passing up a bargain?