This video shows how you can transfer mp3 files between two iOS 7 devices that are not jailbroken. You need to download Music D/L free or Pro version which is only $2.99 and you can download music and videos from the website or sites of you choice. In order to get to the option for AirDrop You just need any app that supports open in for mp3 such as whatsapp or dropbox.
Directions – Open “Music D/L” navigate to files once you’ve downloaded a song or two. Select the “I” or info circle and click “open in” option. If you have iMovie installed it should show the option for AirDrop on the top. Make sure AirDrop “Everyone” is enabled on all devices and click the AirDrop icon and the device you wish to send the file to should show up. It may take a little bit for the device to show up, so you may have to try a few times. Post your questions and comments below and I’ll try to help if you run into any problems.