I have an Onza "parts brake" in silver i'd consider parting with. it actually works fine but the finish isnt the most beautiful, one of the springs is stretched and there is a small crack on one of the clamps from being overtightened. In either case, it isnt perfect but at least this way you would have some spares and it wouldn;t be hard to finish the pad holders black (brake is silver)
If you are interested ill get some pics up later