I recently just acquired the 5DMKII and currently looking for extra spare batteries. To my shock, the new genuine canon batteries are £45 on amazon. Very expensive for my budget if I wanted a couple. Third party batteries for the 5DII are less than £10 each. Does anyone know if these are just as good? Im going travelling and will carry 2 batteries. one is always a back up. when the genuine one dies, I will put in the back up, use that for the day and then charge up the dead one ready for the next day so I only need a battery that will last me 1 day as a back up.