Need A Songwriter And/Or a Song purchasing website?

hello my sister is in the process of being in the recording studio but she's been only recording karoakes and stuff and i was wondering if any one would write a song with a beat and let us have it to record and her genre is pop her role models are like miley cyrus, hilary duff, and demi lovato and she is young like they are so she wants to write songs for a younger audience but mostly i would want songs aboout being comfortable in your own skin and there could be love songs or just songs that have not meaning at all and are just cool to listen to and also if you guys and girl know of any sites that have songs for sale in the pop category and are in the price range of about up to $150..thank you guys please help out in any way you could see ya