Around iPhone 5 Apple started to put up additional $100 USD to ALL iPhone price in HK, as a way to combat the black market trading,
This post is informative, but can I suggest that we not adopt the "black market" nomenclature for cases where people buy hardware in one location, and then re-sell it?
Companies like Apple may brand this a "black market", but that implies that companies have a right to perform perfect price discrimination across the world.
https://en.wikipedia.org/wiki/Price_discrimination
I suggest we reserve the phrase "black market" for cases where contraband is being exchanged, or for cases where items were obtained through crime (e.g. the sale of stolen goods).