Feature Request: Child pricing by amount Variable seat pricing cost

[MaximilianoRicoTabo]

• Add new price setting option
• Revamp JS file.
• Add markup to support new options in edit-level file
• Add new option to checkout page

All Submissions:

• Have you followed the Contributing guidelines?
• Does your code follow the WordPress' coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

Resolves #21

How to test the changes in this Pull Request:

1. Checkout this branch
2. Go to admin
3. Play with the settings.
4. Save a level with variable model pricing and an appropriate range
5. Try checkout page with diffferent ranges

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you successfully run tests with your changes locally?

Changelog entry

Enter a summary of all changes on this Pull Request. This will appear in the changelog if accepted.

[andrewlimaza]

I've converted this PR to a draft as it may require more work to the UI/UX side of things but it is a good start.

[dparker1005]

Before we merge this, we need to clarify between two similar, but distinct, pricing models.

If we take this example:
From 1-5: $100
From 6-10: $90

If a user purchases 8 seats, some sites may expect this to charge $720 ($90x8) and some sites may expect this to charge $770 ($100x5 + $90x3).

The distinction that needs to be made is whether "if you buy between x and y seats, each seat costs $z" or if "the first a seats cost $b, the next c seats cost $d, etc etc".

I think we eventually want both of these pricing models, and eventually we'll probably also want one where purchasing between a and b seats is a flat price of $c, purchasing between x and y seats is a flat price of $d, etc etc

[dparker1005]

Stripe does this really well. See volume-based pricing vs graduated pricing in their docs here: https://docs.stripe.com/products-prices/pricing-models#tiered-pricing