Foraging for food in a foreign country
It does not hurt to repeat that as you arrive in your host country, many of your ideas as to how the world works will be challenged and seen as assumptions tied to a particular location. Beliefs around food as one of the first survival needs will be the first one to go.
It does not hold universally true that Mexican food and burgers are cheap, different countries have different cheap fast foods. Many countries in the Russian sphere of influence, for example, have cheap food originating from former Union Republics. Take as example the cheboureki, fried flat meat pies from Georgia that may be had for equivalent of less than a dollar-- in Estonia at least.
Read more about this food at Gastrologica.