Highlights in the new building?

- Daylight spotlights can be very helpful.
- "free@Home" bus system
- flush-mounted trunk cable

I want to emphasize that some of the positions mentioned here are anything but cheap.

Maybe this thread should be renamed to costly highlight

People... you can do many things... but what is, as the OP asks, cost-effective? So far, only the following from those mentioned have caught my attention:
Bathroom door lock with rotary knob (+15 euros)
Socket in window recess (+30-50 euros)
Outdoor socket (+30-50 euros)

Everything else quickly costs +100 euros or even one zero more.

Sorry....I completely overlooked the cost-effective part The special glazing was less expensive than feared: 250€

We have:

- floor-level shower with seat, shelf, and rain showerhead (~€800)
- LED spots in the shower (~€215)
- flush-mounted radio in the bathroom (~€220)
- 2nd bathroom
- various additional sockets, switches, LAN connections, etc. (~€1,500)
- more expensive clinker bricks with differently colored joints (~€1,500)
- satellite system (~€1,000)
- more expensive wood-look tiles with brown joints, as the original ones were no longer available (~€1,000)
- motorized exterior roller shutters (~€4,600)
- air-to-water heat pump with controlled heat recovery instead of gas heating (~€5,000)
- underground cable for future carport (~€200)
- lock with ventilation gap for the front door (~€160)

Otherwise, I can't think of anything else at the moment, but I'm sure I forgot one thing or another.
Yes, yes, unfortunately it all adds up somehow. After all, in your own home, you don't want to make too many compromises and want it to be better than before. Somehow, the more you spend, the more you want to cry.

Yes, yes, unfortunately it all somehow adds up. In your own house, after all, you don’t want to make too many compromises and want it to be better than before. Somehow, with every euro more, you get the crying

True!! I add: The crying or arguing!