Visa application fees at the consulate, or the Form I-129 fee if a change of status is filed inside the United States at the amounts in the USCIS fee schedule, Form G-1055; plus legal and accounting fees, an inventory valuation, escrow costs and working capital to keep the yard stocked after closing.
Leave room for the working capital the yard will swallow
The dominant number is the investment itself, which must be substantial in proportion to the cost of the business and genuinely at risk. Around it sit smaller lines that still need budgeting. Government fees appear in the USCIS fee schedule for filings made with USCIS and in the State Department's tables for a consular application; Canadians ordinarily apply at a consulate.
Professional costs include a U.S. immigration attorney, a business lawyer to draft the purchase agreement and lease assignment, and an accountant to value the inventory and document the source of funds. One expense is easy to miss: a lumberyard consumes working capital, and a buyer who spends everything on the closing has a stocked yard and no ability to replenish it, which undermines both the business and the case for a real operating enterprise.