Is the budget for a prefab house (turnkey) realistic?

Why actually a prefabricated house? Tendentially, a prefabricated house is rather more expensive, as one often hears.

It is rather unlikely to manage that with the budget using solid construction either. Ours was solid with a "cheap provider" and, as I said, still a few years ago and with a super cheap plot within the range that the OP mentioned. However, prices have risen significantly since then.

Why actually a prefab house? Tendenziell is a prefab house rather more expensive, as one always hears.

Even with solid construction, one is unlikely to manage that within the budget.

Therefore, one does not need to address this question detail.

Now we are very interested in a turnkey prefabricated house.

Does it have to be a "turnkey" house? Only one option comes to mind. A initially small modular house that can then possibly be expanded once the market calms down or your financial situation has changed. Or maybe a townhouse?

Regarding the modular house, I have already seen advertising from a well-known German prefabricated house manufacturer who also seems to be reputable. Since I don’t know if I’m allowed to mention a name here, I can only encourage you to google it. Prices are also listed on the internet. It seems financially feasible for you (the price per square meter is of course higher than for larger houses, but that’s always the case, just like the km-price for tram rides is higher the shorter the distance ;-) ) and the houses are, in my opinion, appealing. As already mentioned, later expansions are also possible.

Regarding the plot of land, it would be crucial to know in which region you would like to build.

When our final settlement is available, I will gladly share the figures here in the forum in a corresponding thread; I do not want to publish an incomplete list.

I keep my fingers crossed for you and wish you much success. :)

We had a selection appointment last week for our prefabricated house (a semi-detached house) with around 125 sqm of living space (including the utility room, which normally does not count towards living space). The construction contract was signed about 15 months ago; unfortunately, there were delays. In any case, we are also going for a turnkey solution and ended up at just about 340k only for the house after the selection appointment. The equipment is "upscale," meaning electric shutters everywhere, enough sockets and network sockets, etc.
If we were to sign the same contract today, the house would cost around 400k... So much for that.
But looking back, with prices exploding like they are, building turnkey was indeed a very good choice—and having completed the financing already last year. :)
The additional construction costs will probably also amount to around 40-50k. The plot is—as already mentioned—very individual.