Hey Vid, there's a new product that came out: Acrylic paint markers from Liquitex.
Have you tried them ?
The black is real black, compared to the Sharpie which looks like a dark blue-purple when you see them side by side. It is a bit more opaque also, and doesn't streak as much. I really like it.
I guess it will not smear when cleared like Sharpie and oil-based paint markers right ?