Cheaper

No. Because then people would see what he was building. It would draw attention, involve local authorities and insurance investigators, require permits and inspections and would make the construction of a massive secret underground lab impossible.
Gus does not only want the purpose of the space to be a secret. He wants the very existence of it to be a secret. If no one knows it is there, if it isn't on the books anywhere, there is less chance of it ever being visited or discovered.

[none]

Money is not a problem

Cheaper, but stupid. The whole idea is to keep it a secret while building it and while in operation. It has to be so secret that the cartel doesn't know nor the DEA. If either finds out, then it's gone as we saw in BrBa.

That said, I think we know what's going to happen to the old German guy. Gus got the report from Mike.