The connections are installed by the construction company, so we "only" have to connect the sanitary fixtures.
We paid net with installation each: - 400 hand washbasin guest WC - 1900 double washbasin with base cabinet - 700 WC - 1200 floor-level shower, rain and regular shower head - 700 glass partition/pivot door - 750 170 cm steel bathtub - approx. 300 for towel holder, toilet paper, etc.
In total 10k€ gross for two bathrooms with two showers. All Grohe, Villeroy & Boch, Keuco etc. - modern look. We did not compare or sample. If you buy the stuff yourself and have someone for the installation, it can also become significantly cheaper. There are no limits upwards either.
I would inquire who can install it for you and simply have them write an offer. Alternatively, assume 10-20k€.