The inexpensive Cowboy shoulder support gets a nice little discount and falls to about $17 bucks. [Thanks Serge]. This shoulder support is often considered a chest clamp and can be a true hands-free shoulder rig without the need of counterweights. It's possible to expand on this system by using rails sets like the updated Rig X - B version from Express35.com.
I also have an old video showing some rails on this shoulder support (here). The Cowboy Shoulder Support is on sale right now via Amazon (click here).
Cowboy Video Camera Shoulder Support