Two stores can look the same and cost completely different amounts to own. What separates them is decided before any design work starts.
Catalog structure is the first one. A hundred products in four categories is a different build from a hundred products that each come in three sizes, two finishes and a made-to-order option, because the second one has to express variants, stock per variant and rules about which combinations exist. That is not a design decision and it cannot be fixed with a template.
The second is how many places have to agree. If stock lives only in the store, the store is the truth. If it also lives in a warehouse system, an accounting package and a marketplace listing, then something has to reconcile four numbers, and that something is either an integration you paid for or a person doing it by hand every morning.
The third is the checkout. Every payment method, shipping rule, tax case and discount type is a rule the checkout has to express and someone has to maintain. Stores rarely get expensive because of how they look. They get expensive because of how many exceptions they have to handle correctly.
So the useful first conversation is not about design. It is about what the store has to do on an ordinary Tuesday, and who is responsible when an order fails.
If you are not sure a store is what you need yet, the broader web design decision covers what to build and who builds it. Everything we take on sits under our services, and the industries we work in shape what a catalog has to handle before anyone opens a design file.