Sony seems to be selling whatever they get in stock within 24 hrs, while the Xbox seems to take days/weeks to sell out, if it sells out. I think it has more to do with demand than it does with supply. On Amazon, for example, the PS4 got more stock a couple of days ago and was sold out before anyone really noticed it. It moved to #1 for a few hours, so it must have had decent stock. It's still #9. The Xbox One, on the other hand, has been in stock for days now, still has over 1K in stock, but only reached #10 and is moving down now. Again, it is still in stock.