For paint, I have a big collection of latex paint, both what I am using to redecorate the house and what my mom had left over from various projects. My plan is to use those colors as a base paint and then mix with the acrylic paint that I have. I have a ton of the cheap bottles of acrylic craft paint and some of expensive (comparatively) artist acrylic paint. The artist paint has much more intense pigments so I plan on doing base colors with the house paint, then add in more color with the craft paint and finally highlight with the artist paint. I think the majority of the color will be sky and water so if I use the house paint, tinted with some of the craft paint, I think I can cover 75% of the mural with the cheapest paint. For the color blocking I've been using the craft paint because I need very little. I watered down the paint to about 50% and so far a little has gone a long, long way. Also the craft paint is already mixed and is just easier to quickly get some out and slap some color on the wall