Build on Apple & Android apps

I need a pricing estimate and timeframe for this. Please provide pricing to build on Apple & Android (front-end use) along with web for the back-end maintenance only (if it is easier to do so instead of on iOS or Android for back-end servicing) for the staff who would own / run this. There is no web browser need for front-end consumer use. If it costs less to build for just iOS (and do Android later), let me know that cost and timeframe for that as well. If you anticipate a recurring cost following the launch of the platform, please let me know that as well as specifics. The mobile application is designed to solve a problem most people have when Working Out / Excercising; finding a Workout Partner. The app can help you find a workout partner or book a session with a personal trainer. The use of the platform by the consumer user is free. Personal trainers can also build their profile for free. So Users that want to workout with a workout buddy, may use the app free of charge. To workout with a Trainer or register as a Trainer, bank information must be entered to send and receive payments. Credit card use is not noted at this time but that may change. The only time money is processed through the app is when a consumer books a session with a Trainer, for which the app platform takes a processing fee for enabling. Please note -- To include an Optional Payment Feature (please provide as an Optional Cost) to allow Advertisers to upload images and/or GIF animation files to appear as advertising banners. Advertisers can select the placement (top or bottom or right rail), geo locations desired, gyms desired and timeframe to run (in month increments). The ads only run / appear every 15 seconds before showing the next ad & there is no limit at this time on how many ads can appear so that when the end of the ad list is reached, the ad loop starts from the beginning. This system should allow internal staff to add or remove advertisers as well as change the sequence of the ads showing. Payment is processed in the app, so the ad platform is all self service by the advertiser. Back to the main app use, the primary (User Member) & secondary (Trainer) uses start by setting up their profile. First, they select their account type (Workout Member or Trainer). Experience and licenses will have to submitted and verified (not sure if online verfication is possible for this licensing since licensing comes from 2-4 major accredited organizations who would need to check their data - open to your ideas) for Trainers in order to be activated on the platform. Trainers will be able to take a picture of their certification in-app to submit it (then in the Back End, the staff verification team will then review, confirm licensing and approve or reject the account. Accounts will have to remain out of network until approved in the back end by a verification team member). There should also be the ability to connect with Facebook as well. Otherwise, they will need to create an account manually. Next, data would be provided on their workouts, goals, training experiences, partner gender preference, preferred gyms, travel distance limit, first & last name, phone number, email address & social media links. Users have the option to include their weight, height and other body specific information to track their progress and perhaps matching purposes for partners. They can also upload a profile picture and write a short bio. Users can be rated based on accountability & interaction experience, just like how Uber drivers are rated after a ride or how you rate others in OfferUp after a transaction. * Users can direct message each other as well as 'request' to workout with other Users if they meet the preferences noted. * Users can block each other.