There is no set amount in the Regulations as what qualifies as substantial.An investment of at least $200,000 is considered substantial by most. However, it is not fixed and an Invest of much less can qualify, depending on the nature of the business. Ideally $200,000 would be the most appropriate figure.
Note 1: These figures are not the regulations of the USCIS, but they reflect our experience in these cases over the years.
Note 2: If the investment becomes equal or greater than $500,000, you may petition for permanent immigration status if you meet the required criteria.