I have painted my hives a very light grey. Wisconsin winters can be very harsh and the summers can be very hot and humid. A very brutal combination for wood, especially for a soft wood like Pine which will contract and expand alot with these extreme variations.
Instead of using different colors for the bodies, I have made stencils of a Triangle, Rectangle, Circle, Square and a Wavy Line. These I spray paint just above the hive entrance in black paint, each hive a different shape and no two hives with the same shapes near each other. Much easier to me than using color combinations and diagonals.
Since I painted buildings for almost 30 years, I can't help protecting my invesement. I use acrylic primer and three coats of semi-gloss paint on the exposed parts and two finish coats on the stacked edges. For me it cost $143.00 U.S. per hive. These are unassembled parts from Dadant. Commercial quality Two Deeps and Two Mediums with frames, foundations, Queen Excluder, Bottom Board, Inner Cover and Outer Telescoping Cover. I also water proof the top of the Masonite inner cover and the inner surface of the Bottom Board.
I did some figuring and it will cost me about $2.00 U.S. per hive for the materials and about 2 hours labor per hive complete for the painting and waterproofing. In the long run, I think this will pay for itself.