While earth governments should acknowledge martian real estate titles the important point is that martian colonists should fully support the idea. Martian title agencies should be established on mars for that purpose.
432 plots (2000 sq.m. ea.) with a minimum bid of $1 can be auctioned off a single sq. km. with the title agency establishing the legal definition of each plot. To bid, each bidder must make a minimum $20 non-refundable deposit into the mars colony trust (which can be totally spent on bids.) Bidding is closed on any plot an hour after the final bid for that plot. Bidding is done on earth with the results sent to the martian title agency. New plots are added to the auction as soon as the title agency establishes the legal definitions. New plots can be multiples of the basic 1/5 hectare size, but the minimum bid of $5 per hectare is retained.
The money in the trust is banked on earth. It is only used to pay for transportation of a colonist to mars providing them with a minimum to the surface of 100 kg of personal property, a spacesuit and a month of consumables. Ticket prices will be $5m or below (in competitive bidding) regardless of the actual cost. This provides transport for a minimum of 60,000 colonists, but much more should land values appreciate (which naturally occurs with occupation and development.) At $20 per plot we can pay for over a million colonists.
New colonists will not starve with only a month of consumables because the colony will have sufficient consumables on hand to support them. As a matter of fact, much of the consumables new colonists will bring with them are likely to be exotic trade goods (like coffee?) rather than personal consumption items.
Note that no government approval is required but will in fact occur as more title holders grow. Trading of titles on earth will probably not happen until governments establish laws acknowledging the legality but that should be no impediment as long as the martians themselves fully back the titles which paid for their transport.
Update: I decided to send an email to my AZ representative in terms of economic development and millions of voters. Let's see if it gets a response? (They're coming to take me away... ha ha.)