Beyond the filing fees published in the USCIS fee schedule, Form G-1055, an off-site case carries costs the employer rarely budgets: legal review and probable amendment of every customer service agreement, and the travel and accommodation pattern that has to be documented as part of the petition.
The contracts are the line item people forget
The petition has to demonstrate that the petitioner keeps control of the work, and the customer contracts are the first place an adjudicator will look for a contradiction. Reviewing them is legal work; amending them is negotiation with customers who have no interest in the immigration consequences and may resist. Both take time and money before anything is filed.
Add the internal cost of documenting the knowledge itself, because the material is scattered across files, controllers and one person's memory, and someone has to organise it. Then add the ordinary items: filing fees per the published schedule, optional premium processing where a commissioning date cannot move, and the travel and lodging pattern for a technician who lives out of a truck for much of the year. The fee schedule is the reference for the government charges; everything else is a project budget.