Payment details? Just zap a 1000 sat invoice every once in a while. We need to breakdown basic cost per zap for running nodes and it will probably be less than 0.1 sat per post, 1sat/note/month for note durability and further charges for image upload. A few market can develop and clients can dynamically choose relays based on fees and reach to followers. None of this will be expensive but building the incentives right will create innovation on the infrastructure side not just the UI/client.