The only cities where an iPhone is more affordable, in the world, are New York, Copenhagen and Zurich.
In 2009, a study compared average salaries with cost of living, and found that, in the average Chicagoan would need to work about 12 minutes to earn enough money to buy a burger. The global average was closer to 38 minutes.
As of 2012, it would take 11 minutes in Chicago (tied with Toronto, Los Angeles, and Luembourg), compared to 9 minutes in Tokyo, and 10 minutes in New York or Hong Kong. (more here)