The immigration charges are modest and published; the licensing and certification costs are the substantial ones. Budget for the state board, the certification body, verification services and duplicate documents.
The regulator costs more than the border
The government charge for a port-of-entry application is small and published, and the USCIS fee schedule sets the amount where an employer files a petition instead. Around that sit the costs that actually matter in this profession. A state board application carries its own fee, as do verification of education, verification of the Canadian licence, fingerprinting and, in some states, an examination.
The health care worker certification is charged separately and requires documents sent directly by institutions, several of which may charge for the service. Add certified translations where anything is not in English, courier costs for original documents, and the expense of keeping the Canadian licence in good standing while the state application is pending. Employers sometimes reimburse part of this; ask before assuming it, and get the answer in writing.