At Moon.com, Julie Doherty Meade compares specific costs of living in New York, Mexico City, and San Miguel de Allende. Meade’s writing is engaging and this could be a useful resource if you are contemplating a move to Mexico.
Meade rates Mexico City as slightly more expensive than SMA, which was surprising to me. I would have thought it would be the other way around, though I’ve never done a scientific comparison. I will say that her food estimates are on the generous side: I can definitely find a complete brunch in Mexico City or SMA for far less than 100 pesos a person. But that observation really only supports her basic point, which is that Mexico still offers a great cost of living advantage.
(Doherty is the author of Moon Living Abroad in Mexico)