Ask for a staged scope rather than a single figure. The initial stage is narrow: nationality, available funds, the concept, and a view on the main obstacles. Transaction support, plan preparation and the application itself belong to later stages that only make sense once a venture exists. Paying for all of it upfront buys work that may never be needed.
Beware of a figure sold as the qualifying amount
No universal minimum investment exists, and no minimum number of employees is set by rule, so a promoted threshold is a marketing claim rather than a legal one. Buying a more expensive business to reach such a number can leave capital committed to something the applicant does not want to run. Judge the amount against the particular enterprise's real requirements, and confirm current official fees for the route separately when the time comes.
Hypothetical example: an applicant is shown a commercial kitchen and catering business at a price chosen to match a figure a promoter described as the qualifying amount. A first review would point out that no universal minimum exists, that substantiality is judged in proportion to the particular enterprise, and that buying a larger business to reach a number leaves capital committed to something the applicant may not want to operate. It would then ask what the applicant would pay for this business if immigration were not part of the picture, which is usually the more informative question.