Distributing iPhones at scale for $920 is a different beast than selling a couple of them for $3500. In the latter case, the costs per iPhone for the seller are much higher.
The game for selling $920 iPhones is "find a price point were demand times price minus cost is maximized".
The game in the black market is "find the highest price point at which the inventory sells out quickly enough".
If the price of a black market iPhone is higher than that of the legal-market iPhone, with any regularity, it suggests that $920 isn't a problem, let alone the import tax portion of that: supply must be the problem.
And if the price only hit $3500 in a couple rare situations (errors, morons), I'm not sure why they even brought it up as if it were common, as that fact completely undercuts the argument about the iPhone being too expensive.
That's a written language problem Apple didn't see coming. It not as bad as the situation you get when you try to discuss the new New iPad though. The Le Ferrari has managed a similar achievement too.
But if you can buy it from the carriers more cheaply than the black market, who would pay more than triple that to the black market?
They're not carrier-locked, when purchased direct from Apple for $920, are they?
And if they're selling for $3500 on the black market, exactly how "expensive" can they be, at $920, let alone how could they be "expensive" due the import taxes that result in an official product that's less than one-third the price of the illegal product that skirts those taxes?