We're in the midst of a Commerce 2 build-out for a client, and a key requirement was to preserve their quantity pricing rules. With thousands of products, and different pricing rules for each one, they need the price for each item in the cart adjusted to the appropriate price for the quantity purchased. When validating our plan for Drupal Commerce 2, we stumbled upon some examples of a custom price resolver, and knew this would work perfectly for the need.

Drupal 8Drupal CommerceDrupal PlanetField API