70% of 2.50 is $1.75 which would put them under with current mobile app store pricing of a 30% fee for subscriptions. $3.75 gets them closer but then margin is

70% of 2.50 is $1.75 which would put them under with current mobile app store pricing of a 30% fee for subscriptions. $3.75 gets them closer but then margin is $0.125 which would total to $112,500/yr if all 900,000 users switched to paid which is highly highly optimistic.