The American entity pays the Form I-129 fee and whatever associated fees apply to a petition of its size, at the amounts published in the USCIS fee schedule, Form G-1055, with premium processing optional. Professional fees, relocation and the family's applications are separate, and so is the cost of building the function the petition describes.
The expensive part is the structure, not the filing
Filing fees vary with employer size and the processing option chosen, which is why the published schedule rather than a remembered figure should govern a budget. Professional fees matter more in a function-management case than in a straightforward one, because these petitions attract requests for further evidence and a well-built initial filing costs less than a response written under a deadline. The line most groups overlook is operational.
If the petition says Cormac will direct estimators and a project coordinator at the American company, those people have to exist, and their payroll begins before the transfer produces any return. Building the positions into the acquisition budget is sound commercially and happens to be the strongest evidence available. Add relocation, temporary accommodation, health coverage, and the L-2 applications for the family.