Sorry to sound like a smart aleck, but the LEAST you can do it actually describe what you've already tried on this phone to get ringtones you've wanted.
That said, you do have a microUSB connection on the side of the handset. Ideally you could simply cook up your own ringtones from MP3/WAV files on your PC and transfer them over via the USB cable. Audacity is a free program you could use to make your own ringtones for free. The only question is, does the Sprint carrier software/ROM block such data transfer via USB(?) If you want info on this, head over to Howardforums.com and ask in the Sprint forum there for your options.
I am wanting to get some new ringtones onto my sanyo pro-700. But I am limited in the fact that I have data blocked completely on my phone, and I'm trying to not spend any money AKA get free ringtones. Is there any way that this will work?
And if so, please describe how, because I've tried before.