Now that I can record 4 to 8 hours on cheap KxS cards, I need power/battery. Is/are there any other alternatives to the BP-U60 ($240 B&H)? I now that for the Sony Z1, there are tons of third party batteries for it. I wonder if there is any cheaper battery for this EX1 or at least a portable power pack for this camera that does not cost $240 or if it does, it last longer than the BP-U60 battery pack.