Red has been one of the best selling colors.
Also why it is the cheapest.

Red
Color	pixels	price per pixel
Std Red	1 to 99	.05
Std Red	100 to 9999	.04
Std Red	10000 to 100000	.03
+2 shades Red	1 to 99	.06
+2 shades Red	100 to 9999	.05
+2 shades Red	10000 to 100000	.04
-2 shades Red	1 to 99	.07
-2 shades Red	100 to 9999	.06
-2 shades Red	10000 to 100000	.05