While there have been numerous rumors about a 12.9" iPad, I have yet to see any real proof that it exists. As with all Apple rumors, I want to see leaked components before I take rumors seriously. That rule of thumb has worked well with almost every new Apple device, so I am sticking with it.
A lot has changed in the 3 months since I last touched on this rumor July. Since that time Apple has released a poor quarterly report and they have launched a couple new iPhones and a doubled up on the iPad Mini. Apple is devoting more and more energy to releasing mobile devices, and I think we could see that culminate in a larger iPad model.
I know that I have raised the point that the Modbook was effectively an iPad Maxi, which meant there was no need for Apple to release a similar device, but I think I could have been wrong. An iPad Maxi priced at $800 to $1000 wouldn't be a direct competitor to the Modbook. Those babies start at $2700 and go up from there, so a comparatively cheap iPad Maxi wouldn't even be in the same market.
What's your best guess for the price and specs? It's going to have an A7 chip, obviously (assuming it exists) but how much to you think it will cost?