An anonymous source close to Nintendo is saying they know the Wii U's manufacturing costs and how much the system will retail for.

Total cost to manufacture the console is estimated around $180
Controller’s total bill of materials and components costs no more than $50
Wii U will be no less than $300 when it launches- NFC capabilities for each controller costs no more than $5
Price of NFC implementation in mobile devices is expected to fall below $1 in near future
Controller’s cost will be slightly less than Kinect

Added up, the Wii U could sell for around $300