Everything from one source - yet I obtain additional offers

Thank you very much for your honest opinion

Sometimes buying "cheap" is so good that you buy twice. You have to think about that carefully, because the well-known companies deliver a known quality. You don't know about the perhaps cheaper providers.

I of course understand the objection "some people go to the trouble of making the offer and others only have to enter the numbers." But don't you compare offers from craftsmen? I asked 6 companies for an offer for a planned curb lowering. In the end, I had 3 offers. The other 3 companies did not respond at all. Of the 3 companies that responded, I chose the offer with the best conditions. The company had a very good reputation, could carry out the work promptly, and was coincidentally also the cheapest.

Yes, sometimes. Sometimes quality is more important than the price. You just talk to the companies and let them do the work. Then you also notice if someone has forgotten something. The customer is interested in the best price-performance ratio, in the right one for themselves, and not in a cheapskate. Blackening has a certain scent.

This is about offers to a construction contractor, whom every involved craftsman knows which colleagues from other trades he will be working with in a team. This is not the same as the involved craftsmen making their offer to some nobody who happened to find their fax number in the Yellow Pages. These offers are already cheaper than they would have been to an unknown new customer – also with the consequence "cheaper than this is no longer fair"!
To even consider the intended method is not only mean towards the craftsmen but also falls under the category "only fools cut sums" for the clever organizer himself.

But don't you compare offers from craftsmen?

GU means to me that someone (more or less) carries out everything. Whether they involve subcontractors for that or combine all trades within their own company can, in my opinion, be ignored.

Do you really think that such a person would then change their offer for trade A or B just because you bring in a cheaper offer for that individual trade?

If anything, in my opinion, you would have to get offers from other GUs and compare the big picture each time, which could also lead to the consequence that you might have to choose a completely different GU just looking at the price.

Also: what if the GU said, I’ll take the company you brought in for trade A, but you take care of coordinating this company with the other trades and ensuring they are always ready on time?