Government fees for the visa application at the consulate, or the Form I-129 fee if a change of status is filed inside the United States, at current amounts in the USCIS fee schedule and State Department fee tables; plus legal and accounting fees, valuation work, state licensing costs and working capital for the division.
The investment has to be substantial; the fees are the smaller line
The dominant cost is the investment itself, which must be substantial relative to the value of the stake she is buying and must be genuinely at risk. Around it sit several smaller lines. Government fees are set out in the USCIS fee schedule, Form G-1055, for petitions filed with USCIS and in the State Department's fee tables for a consular visa application; Canadians ordinarily apply for E-2 at a consulate, since there is no E-2 registration for Canadians at a port of entry.
Professional fees include a U.S. immigration attorney, a business lawyer to draft the purchase and operating agreements with the ownership rule in view, and an accountant to prepare the valuation and to document the source of her funds. State contractor licensing may involve examinations and fees.
Finally, budget working capital for the service division's growth plan, because a plan that shows hires without the money to pay them undermines the marginality argument.