Makes sense, I would have thought they would offer muliple colours as standard, just using dye is ok I suppose, but as you say it would wear, pretty quickly if its going to be handled like a PlaRail is likely to be.
@[deleted] - Personally I would prime it as this will help your top coat stick better and it may make the finish smoother as well so you get a more professional finish, but of course you can just go ahead and paint it as is 🙂