I looked into the megatones at T-Mobile. Turns out they call them HI-FI ringtones and you get 15 seconds of the song. They cost $1.99 and interesting enough T-Mobile calls their regular Polyphonic ring tones megatones. Sadly, my phone can't do HI-FI ringtones.

don't know if this is too late, but i have tried several of the providers and have found that where i live (in outlying areas) verizon has the best and most consistent reception. those i know who live in nyc say that at&t has better reseption in the city, and i have no idea why: it doesn't work at all where i live.
as to privacy, i just don't give my cell phone number to anyone unless it is someone i always want (or need) to talk too....