You can order ps4 launch edition on Amazon.com. it just the demand is so great they have like 5 sku. At my local gamestop they are still taking ps4 preorders and they already 5:1 advantage to xbone.
Gaf is the source for a ton of leak info. The guy has been correct in the past with info but these are just estimates so take them with a grain of salt. The yield numbers he said came from a insiders source in the chip industry.
We also have the leak gamestop memo From friday that states the ps4 preorders "flood gates are open." That's less than a week after the gamestop CEO stated they would buy every ps4 Sony can make.
Flood gates were open for the xbox 360 also. It resulted in people who had preorders not getting thiers till spring of 2006.
My sister and I preordered out xbox 360s a week apart. Both 20 gig consoles . I got mine launch day , she got hers the first week of January.
So when gamestop actually gets the amount of units it will receive for launch day you will see a lot of people getting called and being told there was a delay on sony's part and they can't fill demand and perorders will be pushed back. This will likely happen a month before launch.
At that time no one else will have stock avalible and so the majority of people will just wait. All the while Gamestop is sitting on a $100 + per peroder (some people order games / controllers / headsets / or put more than the minimum per order down) and would have been collecting intrest on it for months. Its a win win for these companies.