Stripe
https://stripe.com/docs/api/products
https://stripe.com/docs/elements/migrating
https://stripe.com/docs/elements
https://stripe.com/docs/checkout/php
https://stackoverflow.com/questions/33521404/make-stripe-data-amount-use-a-dynamic-with-a-variable
https://gist.github.com/bkrausz/a76f9d7a9b446337d470
https://jsfiddle.net/ywain/g2ufa8xr/
https://stackoverflow.com/questions/19281092/create-custom-amount-in-stripe-button
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