well first of all it's the females that produce the eggs, you can have 3 males and one female, and you only get one clutch, let's say you have 3 females, and breed one pastel male, all 3 clutches will have some pastels in them. so males are cheaper cos theoretically you can get several clutches from the females with only one male, lessening the need for males

this isn't a very good explanation, i'm sure others will provide a better answer