The price of electric cars will go down as more people begin to buy them and manufacturers can afford to sell their cars for a lower price as they obtain profits due to the volume they manage
Your analogy doesn't make sense, if many people start to buy electric car, the price of the car will increase because it have a high demand. What can make electric car is cheaper because there are a lot manufactures can produce a lot electric car, so they need to set an appropriate price in order to make people buy it and not looking on the other manufactures.
That's called economy of scale. Economies of scale are when the more you produce of something, the cheaper it gets. This is because you can spread out the costs of production over a larger number of units you make.
For example, let's say you run a factory that produces bicycles. If you only produce a few bicycles, you'll have to pay for things like rent, electricity, and employee wages, but you'll be spreading those costs over a small number of bicycles. This means that the cost per bicycle will be relatively high.
If you start producing more bicycles, you can spread those same costs over a larger number of bicycles and the cost per bicycle will go down, making it cheaper for you to produce each bicycle.
With electric cars, a lot of costs go into batteries and electronics. The fewer cars you make the more expensive they are. Hope this makes sense.