The corporate ones. Establishing and capitalising the U.S. entity, securing premises and making early hires all precede the filing, and correcting stale corporate records adds professional fees.
The company commits before it applies
A new plant requires real expenditure before the petition can honestly describe it: incorporation, capital, a lease, equipment and first hires. That money moves regardless of the immigration outcome, which is a risk the company should name explicitly rather than absorb without noticing. On top sits the cost of bringing corporate records into a state that will support the assertions in the filing, which in long-established family businesses can be substantial.
Government filing fees are published in the USCIS fee schedule and should be read there because amounts and processing options change. The question to ask before starting is what the company would do if the transfer were refused after the premises were leased, and whether the expansion still makes commercial sense on that assumption.