The red one on the left is for sale. I built the module myself. It's a downboy 933 with an X-binned LuxV, though I don't remember the exact binning.
$110 shipped in the US/canada.
I also have a twisty tailcap from an M3 modified with a two stage switch, PM me if interested in that.
There is a wire from the driver to the center spring. The spring in that picture is "squished down" by the force of the batteries pressing against it. The base of the spring is secured in the delrin by a notch that is machined into it as tx101 noted. It's very snug and extremely hard to remove...