Consider the list price as source for discount

Problem/Motivation

The easiest way to show alterations on the price is using a List price (provided by default in Commerce) higher than the actual Price, which usually goes down for longer/bigger variations of the same product.

I was expecting this module to show me the List price as striked-through and the Price as discounted.. but instead it seems some custom integration is required, or it works only with the Promotions module?

For example how would you show a quantity/duration/dimension-based discount? If I enable the quantity field on the add to cart form, I won't see the price updated while changing the input field, so how should the user know there is a discount before adding to the cart?!

My use case is simple: create 1 week subscription, 1 month, 3/6/12 months, with lowering unit price.

With this feature request I would do it like this:
- put the highest unit price (1 week) as List price of every variation
- set the Price as you want (lower per week for longer durations)
- set the Product Variation display format to Calculated, do not select Apply promotions, do select Apply discount format