Some of the hobby shops carry some that are made by Tamiya and Bandai. If you can't find them at the local hobby shop you can try online. The ones from Tamiya are enamel base paint. Not sure on the Bandai.
Tamiya, I know, makes them in Black (Gloss),Chrome Silver, Gold Leaf, White (Gloss), Royal Blue, Green, Orange, Red,Lemon Yellow, Flat Black, and Metallic Gray.
Bandai makes what they call a Gundam marker (after the cartoons). I they come in different tip sizes and have an ultra fine tip set that could come in handy.