What did you spend on your front door?

I understand what you mean ... but our original request was: What is the additional cost for stainless steel roller tapes? Then, if you look closely, it was also in the plural. So stainless steel roller tapes 150 € MP. How are we supposed to know as laypersons how many are needed. We didn’t want to know the price per piece but the total price. If I buy a car and request winter tires, I would probably also receive an offer for 4 pieces or a complete price. I think the surcharge is for aluminum roller tapes with white covering. Apart from the quantity, the surcharge is crazy too, isn’t it?

Why don't you ask the supplier? Ultimately, it's a horse trade. Say the tapes are too expensive for you and ask if they made a mistake?! But you want them, if necessary you'll buy them elsewhere. Compare with other suppliers, ask there. Or is that the [GU]? Then talk it over with them, etc.

I have of course already done that. He said that it is not his fault either, because everything must be static etc. and in order, and he cannot do anything about it. Of course, it must be statically sound. We really feel f****** about this. We don’t have much of an alternative in terms of time, also because they have special [frameworks]. Unfortunately, they know that too. Can anyone assess whether the additional cost is even reasonable or totally exaggerated?

So stainless steel hinge bands 150 € MP. How are we supposed to know as laymen how many are needed.

because everything has to be statically etc. fine [...] because they have special frames.

I assume that from the provider's point of view this did not require further explanation – from my practical experience, I assume: three bands are unavoidable due to weight and are also mentioned in the standard offer; for an optional item, it is generally common to specify the unit price for a lot size of 1 piece, even if several are necessary (and thus not unfair compared to an offer from a competitor). That laymen do not have the practice "in their blood" is generally forgotten by professionals and without ill will. Unfortunately, today’s margins barely allow giving away two bands as a courtesy.