Cost for an offer

Hi,
we are currently checking out 2-3 general contractors for an offer for a turnkey house.
I drew my own "desired floor plan," and the first general contractor said he would make a house sketch and, based on that, provide us with an offer free of charge.

Yesterday we had a conversation with another general contractor, which we really liked, very informative; he looked at the floor plan and immediately said that it could work, but several minor things (e.g., shower) need to be changed so that the ground floor is wheelchair accessible (our wish). Now comes the part that makes us a bit uneasy.

He said that for a proper offer where neither side experiences surprises, you need proper planning to know how thick walls need to be, how big windows are, etc. This would be done by a house planner who works with the company. However, this would be handled independently from the construction company and would therefore cost us about €500.

Everything sounded completely logical and okay, but you hear a lot of negative things and it just gives you a strange feeling.
My question is basically, is this normal or rather the exception? The general contractor builds several houses here and has a good reputation.
I just don’t want to fall into some trap that ends up very expensive. Basically, I find it okay; who likes to work for free? Only it seems that apparently not every general contractor (somewhere in the preliminary invoice it would already be included) charges for this.

Best regards, me

It was similar for us. A "pro-forma" invoice was issued, which we would only have had to pay if we did NOT build with them. It’s a strange feeling, but ultimately you would have a finished plan for the 1200€ (or so), with which you could build a house.

Receiving a finished plan for 500 € sounds absolutely fine.

Well, you would like to receive a defined service. It is fair for the partner to charge for this effort. An architectural plan is significantly more expensive.

Performance wants to be paid for. Whereas this [GU] obviously wants to get paid for his sales phase. Apparently, this works for him. Nowadays, there are simply many people around who think they want to build a house and then immediately give up if there isn’t a plot right away or the prices become clearer. For a [GU], of course, this is a waste of time and money.

Hi, absolutely I have no problem with that either, I just wanted to know what is more the rule now, since the other contractor is offering it for free for the time being, maybe he also runs the risk of falling into a trap because various things were not agreed upon and it becomes more expensive as a result. As I said, no one likes to work for free. We are just afraid of falling into a trap precisely because you hear so much.