Building Custom Product

Hi there - Looking for some guidance or feedback regarding a customization for a client:

Brief description: Client has a few packages of their product offering that are presented in their store. They would like an option where a customer can "build a custom package" by making selections of the elements of that package. For instance, maybe I need 3 of one item, 2 of another, and 5 of the third item, and I'd like to be able to have it calculate a price based on my selections/answers. Does anyone know of a third-party integration with Squarespace that could do this? Or offer some suggestions as to how it could be done within Squarespace commerce?

Think of it as either a page with all of the possible elements that could come within the package OR a set of questions that are answered with what you would like in the custom package. 

Many thanks for any insight! 

BUMP!