There is no statutory minimum; the investment must be substantial relative to the total cost of the business and enough to ensure the investor's commitment. Government application charges are set by the State Department or USCIS, and professional, valuation and legal costs come on top.
Substantiality is a ratio, not a threshold
The regulations apply a proportionality test: the amount invested is compared with the cost of purchasing or establishing the enterprise. A lower-cost business needs a higher proportion invested; a higher-cost one can tolerate a smaller proportion. Because of that, a Lac-Beauport buyer purchasing a modest service business for a low price will usually need to have paid nearly all of it, while a buyer of a larger operation may finance part of the price with a loan secured on personal assets rather than on the business.
Beyond the investment itself, budget for the visa application fee for a consular application or the USCIS fee for a change of status, each listed on the relevant official schedule, plus a business valuation, a business plan prepared by someone who understands the non-marginality test, an accountant for the source-of-funds chronology, and legal fees. Renewal applications repeat several of these costs, so the business plan should be written with the two-year and five-year reviews in mind.