Government charges are modest and are published in the USCIS fee schedule, Form G-1055, whether the employer petitions on Form I-129 or the applicant is processed at a port of entry. In a case turning on the wrong credential field, the larger costs are educational and advisory rather than governmental.
Price the gap, not just the application
Applying as a Canadian citizen at a land border or preclearance point costs comparatively little at the moment of decision, and an employer petition adds the USCIS filing fee, plus premium processing where speed is being bought. Those figures change periodically, so Form G-1055 is the only version worth quoting. The expenses that decide whether Marguerite's plan is affordable sit elsewhere.
A part-time post-secondary certificate in hotel or restaurant management carries tuition and, more importantly, months during which the American position is unfilled or filled by someone else. A credential evaluation and certified translations cost money where any qualification was earned outside Canada. Advisory time is warranted on the equity and side-business questions, since those are the points where a well-qualified applicant most often creates a problem for herself.
And a refusal recorded because an unqualifying degree was presented has no invoice attached but is answered for in every subsequent application.