“[I]f people don’t buy cars, the price that those who do buy cars pay will have to be higher,” the Supreme Court justice said. “So you could say in order to bring the price down, you are hurting these other people by not buying a car.”
I'm not a big fan of the individual mandate, but I'm less of a fan of bad economic arguments against it.
People not buying cars is a decrease in demand. If you take a look at the handy-dandy Env-Econ 101 explanation of supply and demand, a decrease in demand will cause LOWER prices. If everyone wanted to buy a car, and the production technologies, costs, etc (supply) remained the same, the price of cars would RISE.