Additional bathroom through the builder or just laying pipes?

Hello,
we will have a house built by the developer and would like to have a bathroom of about 7 sqm installed in the attic. The developer would charge about 10,000 euros for the bathroom. Are these costs reasonable or is it significantly cheaper to have only the pipes laid and install the bathroom later? How do you assess the costs?

Is 10,000€ too expensive for a car?

Honestly, no one can tell you that. It depends on the equipment.

So without knowing the exact story, I assume a finished bathroom, possibly with inexpensive equipment, but finished nonetheless. Personally, I don't think €10,000 is too expensive for this. Including equipment, tiles, etc., an external party will probably not make it cheaper. The only option would probably be doing it yourself...

If your question is whether to install a finished bathroom now in an attic planned to be converted later or just to pre-install the pipes: the latter is more advisable. With all the pipes in place, what would later cause noise and mess is already done. Finished fixtures also age unused, and in ten years, you’ll hardly be pleased that a bathroom styled according to today’s trends is already finished. I wouldn’t tie up capital in the fine equipment yet.

However, I assume you mean a construction contractor here. Construction developer sell plots fully built and ready to move into; expansion reserves are rather uncommon there.

Thanks to you, that's what I meant! We will inquire whether it is possible to relocate the pipes without installing the entire bathroom!

whether it is also possible to relocate the pipes without installing the complete bathroom

Why should it not be possible? The plumber does not care how many years later the tiler comes. There are shut-off valves :-)