Hello Marquise,
My wife and I have been intensively planning a house build for about half a year now. We already have a plot of land, but we are planning - like you - a single-family house with about 140 sqm of living space and a basement. We already have several final offers for the house and are currently comparing them diligently. We also plan, as own contributions, only painting and wallpapering work, as well as flooring and the outdoor area. We simply can't do the rest. And we are landing with all offers between about €280,000 and €300,000.
Therefore, I dare to doubt that you will manage with the aforementioned €230,000. That might work if you leave out the basement (and I know myself that this might not be an option, as we see it the same way )