Develop A simple Music-Making Application Like A Stripped Down Version Of ThumbJam

Hi, I am looking for an application building expert to create an application that's like a stripped down version of the iPad music-making ThumbJam. It needs to play only in the pentatonic scale in the key of C. I have written a load of backing tracks that will be part of the app purchase so the purchaser gets a whole screen playing surface (as in ThumbJam but without the complex settings) on their iPad plus a bunch of really cool backing tracks to play along to that are really harmonious so the player always sounds good ( this has been extensively tested out on ThumbJam so I know that it works brilliantly). It would be great if there was a selection of instrument sounds eg. Vibes, synth, harp, flute, electric guitar to choose from too. I have already registered a name for this app. It is better if you can show me the same kind ofwork which you have done before. Thanks