It's new and only about 20 ppl have downloaded so far so barely any revenue atm. I'm using just admob and mopub mediation. Google play developer acct is $25 to sign up and I think it's a one time charge. I'm still waiting for apple's approval to get it onto the appstore. More ppl I know have iphones so hopefully that will spread better. Also apple developer license is $99 per year. Hope that helps. I need more advice on monetization myself haha