What are some music apps to where I don't need Wi-Fi to listen to the music?

So I have an iPhone 4 S and I need a music app that I can listen to music on. The thing is, I won't have internet everywhere I go so I need to be able to listen to the music without Wi-Fi. Anyone know any good apps? Please and thank you.

Added (1). I DO NOT USE ITUNES I DO NOT WANT TO PAY A TON OF MONEY FOR All MY MUSIC I NEED

ITunes comes with your phone…

You already have one: the Music app. The apps that you want don't really exist anymore. Downloading copyrighted songs without using legal means is usually illegal in most countries, so of course Apple wouldn't want that.

If you already have your music library on a computer, you can just transfer them to the iTunes program on your computer, and then sync them to your iPhone.