I am building a fretless six string as my first attempt at being a luthier and I need a high mass black bridge. Any price is OK as long as it isn't really exorbitant.
i love my Ken Smith bridge. It is easily adjustable and has a quick release type stop which allows you to lift the ball end straight up and out of the bridge instead of pulling the string through the bridge which can cause scratches on the body.
So far the plans are mahogany core with walnut top and back laminates. 5 piece maple and purpleheart neck, and an ebony board. None of this is final though since I am still looking for wood.