That figure is useful supporting evidence, not proof on its own. USCIS considers the time and expense of training others as one indicator, but the petition still has to describe what the knowledge is and show that Priya holds it.
Cost is one indicator among several
The USCIS Policy Manual lists factors that may indicate specialized knowledge, and the difficulty or cost of imparting the knowledge to another person is among them, along with whether the knowledge is proprietary, whether it was gained through extensive experience with the company, and whether it contributes to the company's competitiveness. A replacement-training estimate should therefore be part of the plant manager's letter, with a short explanation of how it was calculated: months of shadowing, the size of the model's rule base, and the errors a new formulator typically makes. It should sit beside the substantive description of the model, the authorship evidence and the version history.
On the fee side, the employer pays the Form I-129 filing fee, the fraud prevention and detection fee, any applicable asylum program fee and optional premium processing, per the USCIS fee schedule, Form G-1055. Money spent on a consultant's generic specialized-knowledge template is usually wasted; money spent documenting the actual system is not.