I use Medjet Assist - it's $500 a year but it will transport the wife and I back to a hospital of our choice where our health insurance will cover us. We have recently toured Mexico on a motorcycle so we pay a little more to have the motorcycle transported back home in the event of an accident.
An acquaintance was injured by a wave in PV years ago - her companion had to call around to raise $30K to fly her back to the US.
I'm sure Mexico has some fine hospitals - but if something bad were to happen I'd feel a lot better close to home were I can speak the language and be closer to friends and family.