I think people are overestimating the BOM of the NGP.
The ARM Cortex A9 CPU and SGX543MP4 GPU, display module, NAND flash, touchscreen assembly and LiPo battery are the most expensive components.
By comparison, the 16GB Non 3G iPad has a BOM of $250.60 as estimated by iSuppli back in mid-2010 with an estimated manufacturing cost of $9.00.
Other than the updated A9 and SGX GPU, there isn't a huge difference in BOM pricing here. Anyone who opines that both chips are $100 components isn't fooling anyone. OLED displays are currently available in commercial media players priced under $200 and Sony is almost guaranteed to be their own OEM supplier for the NGP displays, so I don't see the price of these being more than the 1024x768 IPS 9.7" displays used by the iPad.
Personally, I'll wait for iSuppli estimates, but I'm thinking a $300 BOM for the NGP is not out of the question.
