ExtremeTech has reviewed the Logitech MX700 Cordless Mouse :
The MX700 mechanism is fairly complex -- after all, you need power management, a DSP to handle image processing and some firmware to store that image processing software. The sensor is roughly 80% larger than the one used in past Logitech mice. Couple the large sensor size with a 4.7 megapixels per second processing rate, and you get a high "frame rate" -- the number of images processed by the DSP each second. Don't think of this as an $80 mouse -- think of it as an $80 image-processing computer.