After searching a bit in ebay I found a GOLD 2680MAH BL-4D! which I am sure it is not original from nokia (will make your n950 explode )
Is there a big difference in battery life between the 1320mAh BV-4D and the original 1200mAh battery?
Off-topic: the n950 doesn't come with a wall charger, is it safe to charge it with the n900 wall charger? Charging via usb will take much longer compared to using a wall charger.