Build a mobile app for iPhone and Android.

Hello, I am interested in building a mobile app for my business that will be available on both iPhone and Android. I would like a quote for how much an app like this would cost to build, as well as what the cost of an ongoing app maintenance contract would be afterwards for ongoing tech support after the app is completed. Essentially, we create meditation audio tracks that have 3 different "sound layers" on each track. We need this app to be able to combine these different audio track "layers" into different variations of cohesive custom tracks, that customers can then save to personal playlists. This mobile app will need to have the following essential features: - A sleek, professional and modern design that is entirely in black & white colors. - Ability to select from a library of sound choices, that will then be combined into a single custom track that can be saved. - Ability to create an unlimited number of custom, private playlists that will loop automatically. - Our team must be able to continuously upload new audio track options in the future. - Ability to listen to custom playlists offline, when not connected to WiFi. - 7 day free trial and $19.99 per month membership charge afterwards. - Ongoing technical support for the app after development to handle any future issues or updates [we will pay a monthly maintenance fee]. Please let me know how much a project like this would cost, what an ongoing maintenance contract afterwards would cost, as well as previous examples of mobile applications you've built in the past. Thanks!