Cost depends on scope more than on the number of screens. The main drivers are the channels you need (iOS, Android, web), the services you launch with, core-banking and switch integration, security testing, languages and the support level after go-live. Because we start from our own Mobile & Digital Banking Suite rather than a blank page, much of the budget goes to configuration, integration and branding. After a short discovery session we give a fixed-scope estimate, split into a launch release and later phases.