From what I understand, putting a decent road through Baja would be around a third of the cost of doing the same road in the US, per mile. They don't have the same environmental standards, for one thing, or the same costs.
The government also recently made it even easier to sell rooftop solar power back to the grid. It mentions the average cost of solar panels paying for itself within 4 years. Hopefully residents of CieloMar will have very small power bills, another incentive to buy,