The PS3 was plentiful after it launched (due to poor sales). The Wii and Xbox 360 were much harder to come by for about a year after each system launched.
My new PS4 just arrived DOA. I can try a few things to get it working but I am not happy.
But here is a funny thing - Walmart shipped it to me even though there was a problem with the credit card charge on Visa. So I have not been billed for it yet. For some reason my credit union flagged the charge as suspect but I told them the charge was OK. But somehow the charge was denied - or at least Wal Mart thinks it was denied. It has not shown up yet online in my account.
update - it is officially DOA so I have to send it back overnight and they send me a new one overnight. They pay shipping both ways.
For those interested in the horse race:
PlayStation 4 is at 4.2M worldwide.
XBox One is 3M worldwide.
XB1 has a slight lead in the U.S. – about 10%-15% higher sales. However, Microsoft is getting trounced everywhere else – PS4 is outselling XB1 almost 3-1 in Europe. The worldwide gap should widen following the launch of the PS4 in Japan where Microsoft has virtually no presence.
For comparison, the Wii U has only sold about 5.3M units worldwide since its release in November 2012.
This is only an estimate for now. Nintendo will release hard numbers by the end of the month.