Hi,
I have 7 years experience in iOS application development with a lot of applications on Store (please review some of my recent applications from my Portfolio). I think there're 2 option for you:
1. open mp3 link in app and play automatically mp3 with sound music system.
2. Search song with Itunes app, purchase that song and play.
If you can accept option 1, I can help you make this app.
I know you’ll probably get a bunch of lower bids but a good developer will help you fulfil your requirements completely.
Please contact me, I will help you fulfil your requirements quickly.
Skype: nlhdung (Dung Nguyen Le Hoang)
Regards!