Different charging stations will charge different prices per kWh, this is typically around R5.88 /kWh.
A BMW i3 (335km range) has a 42.24 kWh battery, this means that it would cost R243 (R5.88*42.24 kWh).
Electricity is cheaper in some parts of the country, costing as low as R1 per kWh, this means that it would cost R42 to get 335km range from a BMW i3.