They are an elastic resource. The amount being created is responsive to demand. Also, they're substitutable; if people can't afford classic cars, they'll buy a

They are an elastic resource. The amount being created is responsive to demand. Also, they're substitutable; if people can't afford classic cars, they'll buy art, or wine, or yachts, or Rolexes, or a thousand other luxury goods. Land is only imperfectly substitutable, and it substitution has definite economic costs.