Some sellers price all their XX morph at the same price. Some differentiate the A++ and the C quality versions of the morph by price variation. It's just how they do (or can afford to do) business. Big or big reputation names can ask more for morphs because people know they can trust them to back up sales and produce quality animals and not make beginner mistakes like mis-sex an animal. Though perhaps some BPs make it harder to be properly sexed... I'm more of a beginner in that sense!

It's like high white pieds selling for more than low whites, they tend to be more visually impressive, though in the case of pastels, visually impressive babies from impressive parents usually make prettier babies.