Converting Rands to Dollars and vice versa should never be done as this skews the statistics.
Let's rather determine real living costs. There is only one way to do this.
You take 2 people in each country with the exact same job and take a look what one can buy with his money and what the other can.
So, let's start with a Sergeant in the police in SA and a Sergeant in the police in New York. In SA the Sergeant earns around R17k a month and a Sergeant in New York US$7,500.
So, the Sergeant in SA does not have R20k to do this to start with. The Sergeant in New York, on the other hand can afford this 5 times a month.
You can do this test with rent, buying a house, buying a car, buying groceries, filling a tank of gas, Internet access, buying computers, and see how much more a person in New York will get vs what a person in SA will get. The US has a living cost of at least 1000 times lower compared to SA.
This is living costs.