Three years ago Mark and Kristin Carvalho abandoned their lucrative careers in management consultancy to become realtors in the simmering housing market of Phoenix, Arizona.

“Aside from the low cost of setting up as a realtor, the economics in Arizona seemed right,” he says. “You have strong job growth and a lot of migration of people from California, where housing is hugely expensive, and from the Midwest, where the weather is cold.”