Shower bath preparation - have it prepared by the house builder or do it yourself later (empty conduit)?

Hello!
I want to keep the option open for the installation of a shower bath in the attic at some point.
The developer would prepare it for about €800:
-> Connections for cold, hot, and wastewater in the shaft up to the attic, closed as a ring line with threaded T-pieces, wastewater branch DN100 above the raw floor with end cap

Is the price fair, or could I just have a 100mm KG empty conduit installed (about €350)?
Or would the subsequent installation of additional (above-mentioned) pipes into this empty conduit plus connections etc. be too complicated and ultimately even more expensive?
How would you decide if money were very tight right now?

Thanks for your assessment!

The price is set so that it is worthwhile for you and that the developer makes a good profit.

How would you decide if money was very tight?

I am not a good advisor when it comes to saving. Therefore, I did not answer this question.

Let it be done, because with a 100mm KG pipe you are not at all well prepared as the only preparation. Because you need connections for toilet waste water, but also shower waste water as well as water supply lines. And everything should work later with the existing connections. The price difference from 350 to 800 should not be decisive here.

Hi,
so if he already wants 350 euros just for a KG empty conduit, I find 800 euros rather cheap. Definitely get it done!
But - check if you might run into problems with a very long ring circuit. (=Water takes forever to get warm at the tap) or branch connections (the water in the pipes really gets stagnant).
Best regards, Andreas