For one, it doesn't matter if you put a limit or not unfortunately, hoarders, scalpers, whatever term you want to use will get around it.
Some smaller boutique labels like Vinegar Syndrome, Ronin Flix, Mondo Macabro, etc... have a staff of 2 or 3 people to handle everything and even though they put limits, there's still hoarders listing multiples for sale.

In this case, I'm fairly sure that Best Buy simply put a small quantity available up for grabs, take into consideration individuals who order 3 or 4 each because of the high level of probability for damaged goods, and it doesn't take long to deplete inventory.

My guess is that more will show up at some point, so keep an eye out.