More than the filing fee, which is published in the USCIS fee schedule. A refusal on the offsite test usually means renegotiating client contracts, rebuilding the evidence of retained control, and refiling months later, while the commissioning projects those contracts describe sit unstaffed.
Price the renegotiation, because that is what a refusal actually buys
The direct outlay is easy to establish: consult Form G-1055 for the current petition amount and the optional premium processing charge, and add professional drafting and certified translation where records are in French. The exposure that matters is elsewhere. If a petition is refused because the client agreements read as staffing, the group cannot repair the file with an affidavit; it must go back to commercial counterparties, reopen executed contracts, and persuade them to accept a deliverables-based structure they had no reason to want.
That conversation takes weeks, may cost commercial concessions, and happens while installations are already sold. Building the correct structure into the contracts before signature costs a fraction of that and produces a better commercial document in any event. The other quiet cost is the ceiling: five years is the maximum for this category, and an assignment restarted after a refusal consumes calendar time the group may want later.