http://arstechnica.com/articles/culture/wii-motion-sensor.ars/1
"When you think of gyroscopes today, though, especially with regard to heading information, they're around $300,000 and are capable of accuracy of ten-thousandths of a degree per hour so that a 747 after an eleven hour flight can land where it's supposed to land," explained Virginia. "Game controllers, such as what Nintendo has selected, don't need that kind of accuracy. What they were looking for something in the area of one-tenth of a degree per second. [The IDG-600 gryo in the MotionPlus] measure up to 1500 degrees per second; it offers accuracy and full-range motion. We worked towards [a cost of] $1 per axis."
This should mean each gyro will cost Nintendo about $6. The rest of the WM+ components and assembly would probably only cost $4, so I would guess the costs for the WM+ would be about $10. I think a MSRP of $19.99 is likely for the WM+ assuming Nintendo releases a standalone SKU.
Does this sound reasonable or did I read this incorrectly?