Good News! Some of iPad 4 parts and accessories are now available on ETrade Supply.
This iPad 4 Digitizer Touch Screen Assembly consists of digitizer, digitizer adhesive, front-facing camera frame, Home Board, Home button Key, Home Button Board and etc.
The white color of iPad 4 Digitizer Touch Panel is almost the same as that of iPad 3.
Compared to iPad 3 Rear Housing, the iPad 4 Rear Housing has no much difference except the charging port, which changes from 30-pin to 8-pin.
There are still more parts and accessories for ipad 4, please view: http://www.etradesupply.com/apple/ipad/apple-ipad-4.html