Chinese brush painting supply sources can be a bit tricky to find, but there are a few great online sources.
I took a Chinese brush painting class a while ago and loved the discipline of this approach to painting. My teacher supplied all of our paints, paper and brushes, so when I went out to buy my own supplies, I was surprised to discover that Chinese brush painting supplies are often not easy to find.
Chinese brush painting must be done with Chinese color and brushes specifically designed for Chinese brush painting.
If you try to substitute Western watercolor brushes and paints, you will not get the same results. Western brushes are just not cut in a way that will produce the desired results when used in combination with Chinese brush painting techniques.
It can be a bit tricky to find the supplies in art stores. I've actually scoured art stores in a very large city in my area without a lot of luck.
You can find a good assortment of Chinese brush painting supplies on Amazon. Amazon itself offers very small selection of Chinese painting supplies, but there are several third party partners on Amazon that offer a huge range of Chinese painting supplies.
Finally, if you're looking for some books to help you get started or advance your skill in Chinese brush painting, here are reviews of three books I've used myself.
Chinese Brush Painting Supply