Some perspective:
How the US dollar became so important: http://www.npr.org/blogs/money/2014/07/16/331743569/episode-...
US GDP per capita vs China's GDP: http://www.google.com/publicdata/explore?ds=d5bncppjof8f9_&m...
In a nutshell, the cost of an iPhone is ~5% of China's GPD per capita, but will continue to shrink as they grow.