I've found that the quality of the paint is often dictated by the ratio of pigment to vehicle, at least in the lower priced stuff at Michaels. That sort of thing is correctable.Paint is not paint. There are definitely higher quality ones. They will give better coverage and last longer.
By the way this is entirely me talking out of my ass, dealing only with acrylics.
But you can get the brushes and the mixing palettes separate.But oils for a 9 year old are probably a little much.