Developer for Facebook/Mobile app

We are a startup with a focus on music education that are currently looking to create a quiz-based game to be made available through both Facebook and mobile devices(Android,ios, etc). There are two main features that we are looking to incorporate: 1.)There needs to be a way for us to get into the backend of the program to allow us to update quiz questions and other content. 2.)The app download would be free, but there needs to be a system in place for us to receive user payments. If you are interested, we can gladly provide more detailed information. Please don't hesitate to contact us. It would be great if you could include some of the following info: -An estimate of time involved. -An estimated price. -Any of your previous work samples -the more similar to our proposed project, the better! - A resume or link to your personal/company website