http://www.mobiles24.com/downloads/free-mp3-ringtones

It has over 17000 free ringtones. you can even make your own ringtones.
I have downloaded countless ringtones from this site so it is ABSOLUTELY free on their end. After you find the ringtone you want, you have to go to the website on your phone and download it, so you must have internet on your phone, so depending on your cell phone plan, it could cost you if you have to pay per kb downloaded.
most of the ringtones are 30 seconds long.

its great.........