Iphone audio kit

This app will invlove layers of recorded audio playing at the same time. At the first page the user will record audio. At the second page the user will record another file overdubbing the existing file. When the user records the second time, the first recording will play while the second is recorded. This should record seemlessly in real time. I would like to be able to record up to as many layers as possible. Once each audio clip is recorded, each layer will play together as if recorded over on another. The user can save and also re-record each layer anytime throughout this process. furthermore the audio recorded will be played over existing audio that the user chooses. individual audio tracks will be able to be muted or subject to volume control. (see attachment for more information) Example: a person records audio, the person then listens to that audio while being able to record over it, the person then listens to the 1st audio playing along side the 2nd audio and is able to record over that. this pattern can keep going to a minimum of 5 layers. Price for design is negotiable, please don't be afraid to ask questions.