So let's leave the basement out for now. This topic is very controversial internally anyway. There are probably cheaper solutions for storage options, for example a storage room by the garage.
The fully developed plot would cost us about 180,000 euros including ancillary costs.
For the house with around 190m2, I assume 190x1,800=342,000 euros
Garden 20,000 euros
Garage 25,000 euros
Buffer 10,000 euros
makes 577,000 euros.
If I deduct the available equity capital of 65,000, 502,000 euros remain as the loan amount, of which 100,000 euros are granted interest-free, leaving about 400,000 euros. With an interest rate of around 2 percent, this results in almost 1,500 euros per month for the 400,000 loan over 30 years, and 230 euros for the 100,000 loan. Altogether 1,830 euros and thus about 500 euros more than our previous cold rent, then based on a monthly savings rate of 2,300 euros, 1,800 euros remain, of which another 350 are incidental costs, and you actually end up with 1,400 euros per month as the savings portion.