Reed contacts for windows and doors - costs?

Does anyone here have experience with the prices for reed contacts in windows and doors? We want to monitor these and have asked our main contractor about the costs. They now want 185,- EUR per contact including installation. If I look online, I find these contacts for 30,- EUR. So the installation is supposed to cost 150,- EUR. The wiring to the HAR is not included yet. That seems very expensive to me. Therefore, I had suggested that I procure and install the parts myself. I was then told that I would lose the warranty for the windows.

The second point regarding the contacts is the quantity. For double-leaf doors, the main contractor now wants to install one contact per leaf. In my opinion, one contact on the leaf that opens first should be sufficient. Or am I wrong? I would be happy to hear how you see it or how you have already solved this.

39€ per contact + tax.
Plus cabling to the control cabinet.
For double-winged doors, one contact on the first wing is sufficient.
However, an error message may appear if both wings are opened and then only the first wing is closed.
Then the contact reports closed, but the second wing is still open.
You have to decide for yourself if you can live with that.

€: I should mention that this was the price from the window manufacturer, as we are building with individual contracts.

Regarding the prices, I would probably faint.

For us, it would mean that if I had the reed contacts installed by us replaced by the company, that would be over €3500. In self-labor, however, less than €100. That's why I would probably lie down first.

I don't know exactly which contacts are supposed to be installed. But I know a dealer where such parts cost max. €10.

If you buy some that can be screwed on but temporarily stick them to the frame or sash with double-sided tape, why should you lose the warranty? And you can get these parts for about €5.

However, if they are to be installed hidden in the frame and sash, meaning the windows are damaged, then the warranty situation naturally looks different.

Either way, make sure to have empty conduits laid to the windows and doors and not just cables installed under plaster.

PS. I sent you a link.

I have just looked at the offer more closely again. It also offers to install the reed contacts with only open and closed detection. That should then be only 50% of those with tilted. This price seems "normal" to me. I just wonder why the "tilted" variant should cost twice as much. Then I will probably take the ones without tilted.

I don't know how to read reed contacts outside KNX, but here it runs through a binary input. That's why I definitely need 2 reed contacts per leaf to distinguish between tilt and open. That would also explain the double price with you.

We paid 500 euros for 12 contacts (including the terrace door), just for the contacts.

Price from GÜ.