I recently bought a Mogul battery from
this guy on eBay. I received the battery, and it really seems fine. The seller says it is the exact same battery that HTC/Sprint et al ship with the 6800, but labeled differently, ergo unofficial OEM. Seems legit to me. The guy has perfect feedback going back a long way. The battery was about $20 shipped. Shipping was quite fast -- from N.Y., not freakin' Hong Kong. I have no affiliation with this seller. I just like to pass along a good word like this when I think it's appropriate.