ive never used this company but they seem to have an offer on p3 batteries almost to good to be true in the uk £86!!!! check it out and see what you think?
http://www.expeditelectronics.com/dji-phantom-3-professional-intelligent-flight-battery-4480mah.html
http://www.expeditelectronics.com/dji-phantom-3-professional-intelligent-flight-battery-4480mah.html