On a less silly note, the cost of living thing is actually quite interesting because we have the same situation over here between Mexicali and living in Imperial County.
A few of my coworkers in IT actually commute over daily (and use SENTRI) and I've always wondered how much they're able to save by living over there.
One of my staff members also commutes daily from Mexicali and she sometimes gets stuck at the line to cross over if there happens to be an incident (such as a person hiding inside a car the other week). I know for her she's mentioned quite a few advantages to living across the border, one primarily being childcare costs for her daughter (I'm trying to remember the exact figure but I want to say it was $300 for the entire month) compared to this side where it would cost about $500-$600 (and in San Diego it would probably be even higher).
Plus the rent / food costs are much lower in general in Mexicali too and the currency conversion is favorable for USD => Pesos.