The government fees are the same as for L-1A and appear on the USCIS fee schedule. The variable cost is professional time spent turning technical records into a petition, plus translation of French-language manuals and training documents, which can be substantial for a mature process.
Spend on the evidence that answers the actual question
Filing fees are fixed and published; check the G-1055 schedule for the I-129 fee, the fraud fee and whether the employer's size triggers the asylum program fee, and add premium processing only if the assignment cannot wait. Legal fees rise with the complexity of the knowledge narrative, so an employer saves money by preparing the internal document index, training records and organization charts before counsel starts. Translation is often the surprise: a shop that has documented its processes in French for fifteen years may need only the excerpts the petition cites, not the full manuals, and a translator quoting the whole library should be asked to quote the excerpts instead.
Ask counsel whether a request for evidence is covered and whether the quote includes a later extension, since specialized-knowledge cases attract questions. Keep the U.S. affiliate's setup costs on a separate ledger.