there are a few options.. I hate paying for ringtones and I"ve had just about every carrier.
one way to go is thru a website. I've been a member of
www.3gupload.com for some time now, it used to be completely free but now they ask for donations. It's 5 bucks for an unlimited membership.. You upload wav's or jpg's or anything and then depending on who your provider is they send a picture message to your phone or you get a link to download from.
the other option is get one of those data cables for a couple bucks on ebay. I got mine for 2 bucks on ebay for an LG 7000 phone. Then look on sourceforge for a program called bitpim. link coming shortly.. this lets you add or remove anything from your phone.. i make my own mp3 ringers from the latest songs with winamp (free software)
www.winamp.com, tho everyone should know of winamp already.
bitpim:
http://sourceforge.net/projects/bitpim/
pm for specific question, i'll try and answer.