If you can think of something that might be good and my recommendation would be targeting the retirement community of Americans living there which is the majority of the million you quote. Speaking Spanish as has been mentioned is the key to starting any sort of business there and will most likely have to take a Mexican national on as a partner, which can be a risky situation because you don't have complete control. I'm not so sure of the 600k in Mexico City because during a US vs. Mexico World Cup Qualifying Match most of the fans in the US Section, 1000 total, are those flying in from the States. I used to work in Mexico and do speak fluent Spanish. Buena Suerte.