Munro & Associates estimates the cost of the sensor plus installation to be $8 so $96 across the car, and the rest of the cost for the wiring totals to $114[0] all including cost to install them.
From sales alone, ie. 420k a quarter or 1.6 million a year[1], they save $180M in a year and Munro estimates $100k/yr savings in removing them from their inventory.