When you were a kid, if you melted all of your crayons together, you would probably end up with black. To get a color other than black, virgin resin is needed. So if you want red, the brand new red resin needs to be purchased. Same with blue, yellow, green and other colors. Since a manufacturer probably does not stock blue, yellow and other colors in the same quantities as black, there is a premium for the price of the resin. Also, it is very likely that recycled materials are not used to produce blue, yellow, green and other colors, which also makes the cost higher.