The size of the container will of course be critical in determining the costs to insulate it. The larger the size the lower the cost per sq foot or sq meter.
If you are insulating the shipping container to regulate the temperature for a long voyage overseas where variations in temperature might damage your goods, the whole container might need to be insulated adding to the price. If you require cooling for refrigeration then many layers of insulation might be required which will affect the price.
If you require the container to be used for habitation and you’ll be adding heating or air con then tell the contractor and they will add the appropriate depth of insulation required to meet your specific needs.