A few facts. A 300 sqm plot with a floor area ratio of 0.3, which is often the case, results in a house base plate of 300 times 0.3 equals 90 sqm. With us, terraces count, whether that is the case everywhere in Germany I don’t know. This makes the targeted house size impossible. The plot might be suitable for a semi-detached house. Turnkey very often means that painting plus floor coverings in non-tiled rooms plus the kitchen are not included. There are providers where you can order these as extras. Calculate for simple painting work, but properly done, around 5,000 euros plus tax for two floors. Calculate laying vinyl, decent but rather inexpensive quality at 60 euros per sqm installed. Including material. Also calculate around 10,000 euros for a simple but properly designed garden with driveway, path to the house, terrace. Calculate 5,000 euros for a cheap fitted kitchen, e.g. from Ikea, price delivered and installed with their appliances. Calculate 1,000 euros plus for extra sockets, another 1,500 plus for sanitation due to a second outdoor faucet, or utility sink, or a shower enclosure made of clear glass. 2,000 euros for a carport, 1,000 euros for a small garden shed. Then determine the connection costs for suppliers and disposers, and have the earthworks calculated by the general contractor; these can also be several thousand extra. Plus a few small items. Construction water, construction electricity, building permit fees. Then the price becomes realistic. Now comes the personal part. Do you have enough lamps? Furniture? Plants. Except lawn, I have that included with the landscaping. Does the development plan force you to build a fence? That costs money. Karsten