Bigcommerce Extension Custom Pricing

We need a Bigcommerce extension that allows us to charge pricing based on custom logic. We want to use Laravel as the backend of the extension and plan to use the Bigcommerce API to add our products to the cart. The prices for our products changes based on the quantity ordered. We want to define pricing as a base price and a price for additional quantity. Also, some products may be priced in tiers so for example if you order 1 it’s $34.95, 2 is $44.95, 3 is $51.95. Notice we do not want to charge per unit but want to assign a fixed price based on the quantity and define a default amount for anything over what is defined. We would want to define our pricing as price groups and assign each product to a price group so that in the future when prices change we can update the pricing of the group and all products in the group would automatically update. I can give access to our current dev site so that you can see how the pricing works on our current Magento store.
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write down “Big commerce” at the beginning of statement