Well I just found the original battery for sale it seems.
Here
Note: Every single seller of that battery, on Taobao, which all use the same image, are considered "high risk" or "not recommended" by an agent website. Shipping was also 15-20$
This place has the V5 for sale but it is expensive at over $260 USD.
They are still definitely for sale in China,
here and
here at very least. Someone's got to make a battery...