That’s an excellent question, and of course the answer is, it depends. But I’ll give you a few hints, based on websites and web applications I’ve built in the past years.
The first investment you need to make is a time commitment. Don’t start building your website before you have figured out what exactly your website should do for you. Don’t think in visual terms like what exactly you want to display on your website. First think in vivid stories that you would want to happen, once your website is online. For instance you could imagine a person is calling you after seeing a photo of that bathroom you designed. It’s crucial that you invest 20-50 hours into this. Otherwise your website efforts will be undirected and likely lead to poor results.
Once you have captured your stories, it’s time to consult an experienced designer to help you turn your ideas into a website.
Don’t take a package deal (e.g. of a classical marketing agency). Package deals are almost always a sign that someone is reselling a ready-made solution to you. Insist that you value their time, and that you want to pay them for each hour they invest in helping you. Start with a small scope. E.g. say that you’d like some proposals for a website design within a budget of 10-30 productive design hours.
For a small website project this might even be enough budget for the design. But if you like the results, and there’s more functionality you want to cover, just extend the design phase.
Keep in mind that up until this point you shouldn’t have worried about implementation costs of the website. Again, don’t fall for package deals that include design and implementation at a fixed rate. You’ll most likely get a readymade solution, and your website will look like most of the websites out there.
Now it’s time to get proposals for your website implementation. One consideration here is to assess if your website is simple enough to be implemented as a static website. Static websites are easy to create by an experienced web developer. They are also the fastest on the planet. So it’s worth considering that option. The drawback is that, if you want to make a change, you need to contact the developer to update the HTML code. Not a problem for simple changes, but if you want to post articles regularly on your website, a static website will not do. You need someone to build a dynamic website tailored for you, where content is stored in a database, and you can change it yourself.
Hourly rates of excellent designers and programmers range from 100€-300€. Be aware that a higher hourly rate does not mean you will pay more in the end. Often a world class developer can solve a problem for you in 5 hours while a less experienced one needs 5 days.
For a static site with a solid minimalistic layout you can expect between 10-20 design hours and 20-40 development hours. If the design is more involved, like you have some illustrations and interactive elements, expect these amounts to double or triple.
For a basic dynamic site, including a few designed pages along with article publishing you can expect 20-30 design hours and 40-60 development hours.
If you need specialized functionality, such as a price information and order system for your customers, then this can be integrated into your website as well. We are now entering the application development domain, and your website turns into a platform. It very much depends on what you need, but from my experience a lot can be done within ~50 hours of design and ~200 hours of development. Given that your application is well executed it is mostly a one-time investment. Once up and running, your tailored solution can run for years with negligible maintenance effort.
Please be transparent with your budget. E.g. tell your designer and web developer that you’d like to start with a budget of 10,000 € to get the basic version of your website ready, but that you're open to double or triple that budget if the initial results are convincing. At the same time, require transparency from them too. Reassure them that you are willing to pay them for the time they invest, and that you understand that it’s hard to calculate upfront how much time will be needed as requirements can change. But also let them know that you only wish to pay for productive hours, where value is delivered to you. This includes when your designer has a brilliant idea during a walk in the woods, but does not include time for learning a new skill or internal research.
Having a trustful and professional relationship is more important than going with the cheapest offer. Again, a good strategy is to start with a small scope and if the perceived value is lower than you expected, it’s a perfect time to renegotiate. If you are really unhappy it’s not too late to halt the project and search for someone to build on top of the existing work.