If you want your bike to look like a KX, why not just actually buy a KX? I don't think there are not any companies that make black plastic kits or each individual piece in black. If you are worried about appearance, then black plastic showing off every little scratch may not be what you want, anyway.
If no company made black plastic for a KDX when it was in production, there may not be any that start making them since it was discontinued a year ago.
2 strokes for life, the 1995 was the first year for the last style. 1994 was the last year for the previous style. (1995-2006)