What protection against burglary do you have? - Cost estimate?

Yes, we probably will.... I think if you pay around 500 euros for a new plastic window, it is not worth spending 300-400 euros on retrofitting per window.

I have now read quite a bit about the EM3 bolt again. It is definitely cheaper in terms of price, and visually I find it okay in the example video. But what is not quite clear to me: there is this DIN 18104, this standard for burglar-resistant products, and the EM3 bolt also meets it. Can one therefore assume that it is just as good in terms of resistance as the mushroom head locking system?

Yes, we probably will.... I think if you pay about 500 euros for a new plastic window, it's not worth putting 300-400 euros into retrofitting per window.

A window from the window manufacturer does not cost 500€ with installation.
Prices from DIY stores and the internet do not count.

Why don't they count?

Are you installing the window yourself? Is a craftsman installing it? Will he install such a window?

You will have to follow the prices that the craftsman charges here.

At least some of these internet providers work directly with craftsmen. You can add that as an extra.

Windows are, in my opinion, charged per running meter (measured all around once). And it starts at just over 20 EUR per running meter plus travel.

I can’t say for hardware stores, but on the internet window at least partially good brand windows are offered.

Larger elements, which must be installed with a crane, are of course also more expensive.