Government charges are set out in the USCIS fee schedule, Form G-1055, with a port-of-entry application collected by CBP and an employer petition filed on Form I-129 costing more. The larger and less visible items are credential evaluation, certified translation and the professional review of the offer letter.
The fee schedule is the small number in this budget
Because official amounts change, Form G-1055 is the only figure worth relying on, and it should be checked on the day rather than remembered from a previous application. A Canadian citizen applying in person pays the border charge; an employer that prefers a petition pays the filing fee, with premium processing available at additional cost where a start date is tight. Each accompanying dependant is charged separately, which a household planning around one applicant tends to overlook.
Beyond the schedule sit costs that are easy to underestimate. A degree from outside North America needs an evaluation report. Documents in another language need complete certified translations, not summaries.
Having an adviser read the offer letter before it is countersigned costs a fraction of what a refusal costs, since a refused application is a fact that every later application has to answer for.