I guess, you will not find a good original battery for the FP1; at least it will be a rare find.
In the meantime, you might want to take a look at this thread:
The Huawei Battery HB5N1H works fine as a replacement, though it doesn’t fit exactly. You will need something to fix the battery.
But my wifes phone runs on one of the Akku-King batteries flawless since years.