The circle of Dusk mercenaries isn't huge, there are a number of Dusk mercenaries in this world, but there's only one Dusk Territory, and over time everyone sort of gets to know each other.
After a lot of haggling, Zheng Yichen managed to reduce the price of an item valued at 2 merit points by half. Pushing any further was definitely not possible, as the Dusk mercenary needed merit points to resolve the Life-Stripping Curse. He most likely had emergency merit points on hand, but the loss he'd take would certainly need to be recouped from this transaction.
1 merit point, two million, plus three amulets.
Looking at these prices, using merit points to exchange for money in the Dusk was definitely a losing proposition.