Is it better to buy property or not?

Even if no 60K€ equity is to be contributed, but only 50K€, because for example you still need another 10K€ at the end for kitchen, furniture, lamps, curtains, car, or something else in addition to your remaining equity, it would work. You then only state 50K€ equity in your total calculation, pay for the land first, so you initially paid 10K€ too much and have the 10K€ paid out to you with the first tranche. Everything is doable.

Especially since you then have to deal with the notary or land registry office twice. Once when buying the land and registering yourselves, and once when registering the mortgage for the little house.

But it doesn't cost more; since these are two separate transactions anyway. Just slightly more effort in terms of time.

@TE: If you buy now and arrange the financing for the construction project next year, nothing unusual will happen regarding the financing and the value of the land.

On the contrary, it's actually an advantage; because you can calmly gather the costs for the house or properly focus on choosing the right general contractor instead of having to put together a complete financing package in a hurry.

It's definitely worth taking the time to compare banks and intermediaries regarding the financing.

why are you focusing on the money here and not on what the property is like and what you can build on it?

I don't buy a kitchen and then the apartment that matches it

I don't know how it is in Hesse, but in Bavaria, getting a plot of land in a reasonably developed area is like winning the lottery.....you take whatever you can get and you can always put some house on it!