Go to the website for Al Jacobs. He makes an industrial strength rechargeable battery pack for Nikons in several sizes. One is small enough to fit into the jacket pocket of a Tuxedo for wedding scenarios.
You'll save money in the long run. Click on the tab for "Wedding Equipment" on his site. I've got a genuine Nikon SD-9, but though you've got a few extra batteries in it, you can't shoot forever. Maybe a factor of 2X or 3X in terms of power. A big advantage in recycle time, though.