Property with a price significantly higher than the standard land value

He will certainly want the cash payment in advance

Then you would be dependent on his goodwill.....never. Ever.

Exactly. Apart from the fact that I'm simply not a fan of shady deals (even though the rather high taxes in this very tight market annoy me as well), I wouldn't know any way to realistically depict the scenario.

It's just a shame that something like this is practically demanded. But in this market, you can demand exorbitant prices and shady dealings and probably still find a buyer quite quickly...

I know someone where it went like that. The money was handed over in cash directly before the notary appointment against a receipt. Both parties must be aware that the notarial purchase contract is void. If it doesn’t come out, though, nobody cares. So it does work...

I also know someone or some... but those were relatives among themselves

You can also have bad luck if the municipality decides to exercise its right of first refusal, for whatever reason. A low notarized price certainly does not reduce the likelihood of this. And then the municipality only pays the notary fee; the sums that flowed unofficially until then are gone for the time being. Or the seller returns it to the buyer but receives significantly less than hoped from the municipality.

One of the other two parties just pulls a very long face exactly at the moment when the notary/groupier announces the "0" and everything goes to the municipality/bank.