Ringtones are outrageously expensive. My stepdaughter wanted to put some custom ones on her Razr which you might not even be able to download, and I happen to be decent with Audacity. I wanted to put a note on here so the next visitor to google.com would do better than I did.
Make sure your MP3 file is encoded at a 22kHz sample rate.
If you don't do that, you will get the message "File type not recognized" from your Motorola Razr phone.
You will see a lot of stupid nonsense about making an mp3 file and then renaming it to .MID. I didn't do that, I just figured out where the project sample rate button was in Audacity. (Hint: It's in the bottom left corner.) Then export as an MP3, transfer to the phone using one of many methods, and off you go.