The minimum investment for import export business largely depends on the products you are planning to sell and the country you have agreed to trade with. Chances are that you will sign up with a global freight forwarder and opt for a subscription plan for all your shipments. The cost of this plan will depend on the products you are shipping and the country you are shipping it to.
Other costs include expenses for a space to start your office, a storage space for inventory, a packaging facility, obtaining licenses, etc.