Just swap out the sqm in Alex's (in my opinion good) estimate...
150sqm * 2000€ = 300,000
40K€ additional construction costs
40K€ simple utility basement
5K€ carport?? (estimated - I have no idea what something like that costs)
In addition to what has already been said: Carport, depending on size (single/double), rather five-figure, so around 10K€. In my opinion, the basement estimate of 40K€ is also too low; I would calculate about twice that. It also depends on the soil conditions; you might need a waterproof concrete shell (WU/white tank), excavation for the basement is also more and can bring surprises. What I would also add: about 10-15% buffer for unforeseen expenses. And even if you set out to avoid it, the thought of "you're only building once, it should look nice, so let's choose option x over y, even if it costs 500€ or 1000€ more" will come... and you really have to be v-e-r-y disciplined to resist that every time. For example, in our case, the air-water heat pump must be placed in the front garden/street side; the options are Alpha Innotec, Ochsner, or one of these, in my eyes less aesthetic, Far Eastern air conditioning looks. Behind the house is okay, but in front? The Ochsner would be the most discreet, but costs about 4k more... something like that usually isn't included under the air-water heat pump item in the cost estimate.
As already said, the 3 (thousand) is quite unrealistic; it will surely be a 4 (thousand). And plan reserves; they sometimes disappear faster than you'd like. And I haven't heard of so many construction projects where there was a lot of budget left over at the end—rather the opposite.