The highest tier of storage on any iPhone or iPad to this date has been 64GB, whether an iPad or iPhone. The report shows the 128GB iPad will be priced with the same sort of differential pricing as lower iPad tiers.
Each tier of storage rises $100 in price. A 16GB wi-f only iPad runs $499, while the 32GB model is $599 and the 64GB model is $699. This means that the 128GB model would run $799. A wi-fi + cellular version would be $929.
A source from a high-profile retailer supplied the following SKUs:
ME392LL/A (P101 ULTIMATE A-USA), ME323LL/A (P101 ULTIMATE B-USA): black/white wi-fi only
ME406LL/A (P103 ULTIMATE A-USA), ME407LL/A (P101 ULTIMATE B-USA): black/white wi-fi + cellular
The P101 and P103 names are Apple’s internal terminology for the wi-fi and wi-fi + cellular iPad 4s, respectively.
What's interesting si that Apple has previously called its 16GB through 64GB storage tiers “GOOD,” “BETTER,” and “BEST,” respectively, and now we have an additional “ULTIMATE” model.
Developers have also found references to 128GB iDevices in the still beta iOS 6.1, so we'd assume that any release of hardware will wait until after iOS 6.1 final is released.
This could also mean that a 128GB iPad mini and a 128GB iPhone 5 will be coming soon, too. However, there have been no leaks from sources such as the retailer, above, that indicate so.
In addition, there is no indication that Apple will refresh its line with tweaked hardware, meaning that the new iPad will simply have more storage, but no otherwise modified specs.
Update: Apple released iOS 6.1 on Monday. This could mean a 128GB iPad 4 release is imminent.