Ecommerce website designed and built with pricing calculators.

Hello. I require an ecommerce website to be designed and built for me, using wordpress, Wix, Shopify or similar. The website will sell metal shapes, which can then be customised to the customers sizes. The website will need to calculate the area of the shape and then provide a cost for the shape so that the customer can purchase. The website will initially contain 11 shapes but I may decide to add more later.
I will need help setting the payment gateways up and arranging the hosting. I already have a domain.
I do have a reference site I can share.
The successful freelancer must be able to show previous examples of creating pricing calculators.