A reputation system with wandering villagers

How this will work: When you first meet wandering villagers, they will have pretty bad trades (Basically what they have now.) But the more you buy from them, they will come back with better offers and potential discounts. If you kill them, they will have less trades and charge more.

Why: This would encourage people to buy more often from wandering villagers and not just encourage them to kill their llamas for leads