It's a Kinect port extension cable. You can tell because the male end of the cable has an indentation on one of the corners so it can't be plugged into a USB port.
Why that costs $50 is a mystery, but you know someone will end up buying it.
I'm going to take a huge guess here and assume that the $150 price of the Kinect kit actually includes the required AC adapter and Kinect port cable for the near 40 million consoles currently in circulation that aren't "Kinect ready."







