ᐅ Construction of Storage Room + Carport / Experiences and Cost Estimates

Hello everyone,

We are currently in the middle of planning our house. We have a great understanding with our builder regarding the house itself, but when it comes to the attached storage room with carport, we were quite surprised.
They have quoted a price of €20,000. That seems a bit high to us.

The room is planned to be 6x3 meters (20x10 feet) and will be built attached to the house (so it will have 3 exterior walls). In front of it, we want to build a double carport, whose roof will also extend over the masonry room. Afterwards, we want to clad the addition to match the house.
The addition should also have 2 doors (1 facing the carport and 1 facing the garden).
The door leading into the house is already included in the house price, and we have agreed with the builder that the foundation slab for this room will be poured "at no extra cost" at the start.

Has anyone had experience with such a project and can maybe tell us whether it is realistic to build this duo for under €20,000 ourselves?

I have already done a lot of online research but couldn’t find any solid results, as it should not be just some cheap fix but last for several years.

I would be grateful for any experience shared and look forward to your replies!

Many thanks in advance!
Best regards,
Lena