Apple now allows you to buy ringtones directly through iTunes. Unfortunately you have to buy the song first, and then pay another 99 cents to convert it into a ringtone, but only songs in your library with the Ringtone symbol will work.
Can I get free ringtones for my iPhone
Kind of. Any song in your iTunes library can be a ringtone on your iPhone. Before you can upload ringtones to your phone, paid or free, you have to to update iTunes to 7.4 or higher. Then you can use any of these methods listed, or this one I know works.
Is this legal? I am no lawyer, but read this and proceed at your own risk.