The prices that the NPC offers scales depending on the effective rarity of the shiny you offer him. This means the most common species like Pidgeys will see a reward of 4 Pearls, and the most rare species like Shedinja will have a reward of 28. The vast majority of species will pay out 4 - 12, but if you want to liquidate something very, very rare for Pearls, we need to offer an appropriate price.   I'll note also that this is the base value of the reward. Certain multipliers come into