You are right, when it comes to the newer morphs, Males are more expensive, because of what you described before. An expensive Male can be breed to several normal (cheap) females.

When you look at the older morphs, the females are more expensive. Pastel, Spiders, Fires to name a few. Because they take time to grow and be able to breed. So people try to stock up on them.

Supply and Demand as always.