The price for the 7d battery pack isn't as cheap as the 50d one, but from what I hear, the weather sealing on the 7d pack provides better protection that even the 5d mark ii*. On top of that, $130 some bucks really doesn't seem all that bad to expand the capabilities of an almost $2000 camera. I mean, I know money doesn't grow on trees, but I'd rather buy the pack designed for the camera for a few more bucks and get all the advantages than save a few dollars.
*EDIT: As in the 5d with it's personal battery pack. I hear there is room for leaks on that connection between the two components.
I have the D5 MKll and purchased an ebay battery. used as a backup since the D5 was introduced. It has performed well. and the compartment has never leaked. The only issue is the non canon bat does not show the level meter.
Mule Ferguson
ahhh, nice thanks for chiming in on the ebay battery. Ive been wanting to get one just to have as a backup. Maybe use it for an hour or so while the main battery charges, and then switch back. Thanks for confirming it works ok.
Ive honeslty used ebay batteries in the past in canon p&S SD series cameras and had no problems, but i just was a little reluctant to toss it in my 7D that cost 10X what a point and shoot cost.