The things are pretty expensive, so why not build it yourself!
Maybe you could build something like this out of Paper or thin white sheets/Nylon (it needs to be thin enough to let the light through like a diffusor).
It has to be all around your subject (even in front, to prevent reflections), just cut a hole for your lens, and light it from the outside thought the Paper/Nylon from two or more angles. You won`t have the disturbing reflections that way, should be easy to cut out in PS then.
Geometry's at work here. The object's too close to the surround, so the colour pickup is intense. The shape of the object will simply pick up the surround unless it gets move further away.
Here's a radical notion - shoot it outside with sky as background (you'll have to angle it) using a diffuser to avoid harsh direct light. You'll still have to work with relfections, but that could be managed with careful use of your existing materials.