Well, My dad owned a body shop in Redford but has since retired. He more or less specialized on restores and classics, but also did some insurance work. He told me that as a basic rule of thumb:
Complete paint, no body work (i.e. scratches, dents, dings, rust) runs 2,000 to start.
Complete paint with a change of color, and no body work runs 4,000 to start.
Keep in mind that booth time is very expensive, and material (good materials that is) are also very expensive...try 175 bucks for a pint and it takes 2 quarts to paint a car. Pluss clear, plus rubbing compound, sanding material, ect.
So yes, painting a car is hella expensive. OH, AND there is one more rule of thumb, "a paint job is only as good as the body work under it".
Dan