Cost depends on scope and technology. A simple business card (a few pages, no admin panel) is often a few thousand in local currency. A company site on WordPress with several pages and a gallery usually costs more. A landing page can be cheaper than a full site because it’s one page, one goal.
An online shop is a higher tier: product setup, payments, shipping, possibly integrations (accounting, warehouse). You often see ranges like €1–3k for a smaller shop, with custom quotes for larger projects.
On top of one-off costs (design + build) there are usually hosting, domain and possibly support or updates. It’s worth agreeing upfront what’s included and what the ongoing costs are.