I've done the same calculations and right now it costs about 8000 STARBITS to buy 100 fans via card purchases on the marketplace. That will likely increase once these changes take effect, but since the payoff of the millionaire card is 10,000 STARBITS and you'll need to add 100 fans per day to keep it going, the cost/benefit is gone especially because the millionaire mission only provides STARBITS and nothing else in exchange for running it.
!PIZZA