It's interesting that, in the case of the Kia Niro, the 40kWh model costs $68,000, but the 64kWh version costs only $6,000 more. You might have expected that, if batteries were so expensive, the 64kWh model would have cost a lot more than $6,000 above the 40kWh model.
I think there is a bit of cross subsidising going on with only a 6K price for 24KWh of Batteries,
In the US the difference between the Leaf and Leaf + is around 6-7K USD, or 10K NZD, (there are a few more bells and whistles but its mainly the battery difference)
BNEF say the cost of EV cells are around ~170 USD/kwh, so a 24kwh jump is $4100 USD whack on ~50% margin and you get 6K USD,