I've discovered that while I can't connect to my phone via Bluetooth, I can send my phone an email with an MP3 attached, and then save that to the phone. I guess I'll find out how much that adventure cost me when I get my first bill. I assume that 50 KB isn't a terribly expensive file transfer for a person with the most bare-bones plan possible.
Actually, I'm very curious as to what my first phone bill from Verizon is going to be. I'm on a really bizarre plan. I'm sure I'll have more riveting details once I get my first new bill from what I like to call my "Wacky Communism and Gambling Plan."