What may ceiling spots (in new construction by general contractor) cost?

We were given a price without the light fixture.
I don’t know much about this. Do you buy the light fixtures yourself then? Or does the general contractor provide the fixtures during the selection process?

I find the 170 EUR almost outrageous for that. At the time, we had the choice to commission just the preparation (recessed pots get concreted in and wired) or the complete service (electrician also installs a standard GU-10 socket plus the light source). The preparation cost was just under 70 EUR, which given the material value and effort was certainly not a loss-making job for the GC; the complete service would have been 120 EUR, which I still consider far too much.

A few light bulbs don’t cost an arm and a leg, do they?

Of course, it starts in the single-digit euro range. How one likes the light, however, is another question. I believe that the OP still knows little about lighting. There is more to consider than installation location, design, and price.

Electrician is still installing a standard GU-10 socket plus light bulb

Is that actually a bad option? That's how we're planning it now, too. I actually thought that a standard would be the most flexible. Is that a misconception, or is this about expensive "perfectionism" that is criticized as unnecessary cost drivers in other threads? But I don't want to start a fundamental discussion now.

Let's put it this way: It's not my solution, but if it has to be done, I would pay attention to high-quality frames/mountings and especially *my* light bulbs. Otherwise, I simply see no point in using a retrofit solution in new construction when I have the opportunity to plan "native" LED lights from the start.

Is this actually a bad option now?

No, it is not a bad option. It is just not the goal. It is about light in the rooms and a pleasant life in the house with this light. From this premise, the choice of luminaires and locations arises. I doubt that the goal "pleasant living" can be achieved well and cost-effectively with a plan of masses of recessed lights. The system selection is subsequent and subordinate to the goal. And of course, GU-10 systems can be absolutely suitable and appropriate in many places. And of course, it doesn't have to be expensive. Here, intelligent approach pays off fully in budget and result. Therefore my advice as a "lighting expert": educate yourselves and get advice. Light and acoustics are direct factors for well-being in the house and are often underestimated.

There are also excellent retrofit lamps, e.g. those that get warmer when dimmed and have a high CRI value, which supposedly native LEDs, whatever that may be, can hardly compete with. As already said, it always depends on what you want and what the overall concept looks like.