Need to dye plastic. What dye do I use?

Dying black with SEMs off the shelf Landau black is too easy. so its done too often. Other colors ( like the factory red ) are not off the shelf shades and can be difficult/more expensive to match.
I think I would look for a black since it is the most common color.
When that buyer comes along wanting a true red one, you can ask more coin for it.