Just like a quote for your own customers: put together what you need and see straight away what it costs one-off, per month and in the first year. Alongside, you see what a traditional web agency or a do-it-yourself website builder usually costs.
What makes up the cost of a business website
A website costs you twice: once for setup, design and copy, then on an ongoing basis for hosting, domain, security updates and changes. Many quotes only show the first figure. Over five years, though, the running costs are often higher than the build, much like a machine whose servicing you overlook when you buy it.
So always work out quotes over at least three years and check what is included: mobile display, search engine optimisation, accessibility, additional languages and changes are extras with many providers.
Questions to ask every provider
Do the domain and content belong to me, even if I switch? What does it cost to upload new reference photos or change the office hours for the summer? Who takes care of the Impressum and privacy policy? How quickly does the site load on a phone out on site? A low starting price does not help much if every little thing is then billed by the hour.