The government fee at the port of entry or for Form I-129 is on the USCIS fee schedule, and the employer is not required to pay it. The larger costs are the move itself and any income the spouse gives up.
Budget the permission and the household separately
TN has no prevailing-wage or labour-certification requirement, so there is no rule that the employer pays application costs. The fee for a port-of-entry application and the fee for a Form I-129 petition are set out in the USCIS fee schedule and should be confirmed there at the time of filing; premium processing is available for petitions at an additional fee if a written decision is needed quickly. Professional fees for reviewing the offer and preparing the file are separate.
For the Paradise household the larger figures are elsewhere: relocation, housing in the client's city, health coverage during the transition, and the paramedic's income, which stops on the move if he holds TD. Ask the employer to state in the offer which of these it covers and whether any relocation payment must be repaid if the position ends early. None of those amounts affect eligibility, but they affect whether the move is sensible, and they should be known before the resignation link in the chain is reached.