A strange thing is happening: four years after launch, the PlayStation 4 is selling out – particularly online in the United States. To be clear, if you had planned on getting Sony’s system this week, then you’ll probably find plenty of stock in store – assuming you’re willing to fight for it – but the heavily advertised $199 consoles have all but evaporated on Amazon, Best Buy, Target, and Wal Mart’s websites. Not even GameStop has any stock online – although it seems the device is available in store.