Without knowing the size of your airline, it's impossible to assign a dollar amount (and even then, there is not a known formula). The amount of marketing dollars required to move the needle is proportional to the size of your airline.
And unless you are doing a lot of intercontinental routes, a company image of 100 is not going to bring in more traffic. For an all-domestic or short-haul airline, 60-70 is all you need, and spending more to move it higher is a waste of money as there is little to no return on that investment. Medium-haul can benefit from 80-90 CI. Only ocean-hopping routes can really benefit from a CI higher than 90.