http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=29021 open this page, then wait for 5 mins or so and the price will drop to $5.90
it is slightly not round enough to fit in the original hole, and the connector is only a mini-jst, but thats what my glock has, and it works fine (my glock has a 35-70c 300mAh battery, so the 25-50c is fine)