I can only agree with my predecessors. It is best to buy the property directly and finance it flexibly. I know the new development area and it seems much more spacious to me compared to what GEE is currently developing in Erkelenz....
I would also urgently recommend, as already mentioned in the initial posts, to seek out a local construction company. Both the construction company from Schwanenberg and the construction company from Selfkant-Saeffeln are often present on our construction sites and you hear many good things about both. Of course, not everything will always run 100% flawlessly there either, but the general tone is positive. I would simply take a look at various construction sites of the local contractors in the current new development area and just talk to the builders regarding their satisfaction.
At first, I also only had the big companies in mind and later often had to swallow hard when going through the construction descriptions, as what apparently is not standard and has to be paid for extra...