Land on Mars may have a different value from land on Earth. Ownership of the land is conditional to the Outer Space Treaty and the Moon Treaty. The Mars settlement is built on, or in, land, and the various facilities required for the settlers may be owned by settlers. But can the settlers own the land and the resources they contain?
The Outer Space Treaty was mainly written to prevent the militarisation of space. In the case of an eventual Martian Settlement, the treaty would likely need to be modified significantly. In addition, there is probably no real way of enforcing the treaty. The limitations of the treaty have been explored in fiction; in the TV series Mars, a company that was set up to exploit Martian ressources was based in a country that was not a signatory of the outer space treaty.
Who owns Mars
Antarctica is often used as an example of a land body that is subject to a similar treaty ans where ownership of the land is prohibited.
How much land?
Mars is entirely covered with land. So even if it is smaller than Earth its land area is practically the same.