i use the seidio 3200 battery as i have used them with my older 6700. They make great batteries and are U.S. based. I tried to call Mugen and they are based i think in china and their offical website has everything in euro prices. I only usually buy directly from the manufactor when possible instead of someone off ebay. I would stick with seidio and they now have the offical battery cover protector for the mogul...
http://www.seidioonline.com/index.as...ROD&ProdID=994
Plus seidio also offers a whole range of products for the mogul. Keep in mind if you go with the mugen power then they might not have all the accessories that seidio offers.