There is no published minimum. The investment must be substantial in relation to the total cost of purchasing or establishing this particular enterprise, so a modest business requires a proportionally high commitment rather than a large absolute sum.
Proportion, not a threshold
Applicants often ask for a number and are frustrated to learn there is not one. The test is proportional: the amount invested is weighed against what it costs to buy or create an enterprise of this type. For an inexpensive service business, that generally means the investor should expect to commit substantially all of the purchase price and start-up costs rather than a fraction of them. Money held back for working capital can count if it is genuinely committed to the business rather than kept as personal reserve. Separately, budget for costs that are not the investment itself: legal and accounting work on the purchase, the visa application fees published by the Department of State and USCIS, professional fees for preparing the case, and the operating losses of the first year, which the plan should acknowledge rather than hide.
Hypothetical example: A Canadian citizen contracts to buy a custom-sign workshop in Idaho. The decision is not whether a particular dollar figure sounds large; it is whether the funds actually committed are substantial for this workshop's purchase, equipment, leasehold work, and opening costs. The buyer should list every nonrefundable payment, identify money still freely withdrawable, and separately reserve personal living funds. Only the first category is persuasive investment evidence. Capital must be irrevocably placed in the business and exposed to loss, while the resulting enterprise must be real and not marginal. Legal, accounting, translation, and application charges belong in a separate budget, so they are not mistakenly presented as business capital. A common error is holding back most of the price until status is issued; that may feel prudent commercially but weakens the required commitment.