Currently, the 16GB and 32GB Wi-Fi only models are priced at $199 and $249 respectively while the 32GB Wi-Fi + Mobile data models for AT&T and T-Mobile cost $299 each. According to the sources, by the end of this month, more than 6 million units of the tablet will have been sold. The top selling variant is the $249 32GB Wi-Fi only model. The same sources say that by the end of the year, 10 million units made up of a combination of the original model and the second-generation version, will have been purchased. Android 4.2.1 is currently running the tablet following a December update, and it is expected to be the build of Android that will be installed on the second-generation models, right out of the box.