Paint them like you paint your gun. Mags are way easy to get scratched up. Paint them, get it scratched, paint them again. They will get scratched because you throw them in a bag to a game, you shove them into your pouches, and take them out, slide it in your gun, and take it out. Paint will get scratched up in time.
You can buy them coloured, but then, they're just the same shit but painted.