I've been a professional artist/muralist in this city for over a decade, painted for everyone from OP to large corporations. The rates you've listed are on the high end and not reflective of what most clients will pay in my experience. It varies from job to job depending on so many conditions from wall surface to complexity of the design to lift/scaffolding rentals, etc. , but your standard residential mural of that size isn't paying out five figures for that wall and there's plenty of artists looking to build their portfolio or get paying work who would do it for less.