Here's where i got mine."CAMTREE Camera Shoulder Mount Kit" is completely superb product in terms of quality, needs and comfort.
http://www.camtreerigs.com/index.php...t-kit-201.html
And these look to be essentially the same thing at a lower price..
http://www.camtreerigs.com/index.php...low-focus.html
http://www.camtreerigs.com/index.php...v-cmft-ke.html
This is good product and good value for money. I would definetely recommend this product.