This is the one I have:
http://virginmobile.ca/vmc/en/phones...uctId=10-00062
I think it's pretty much the most basic thing available.
$50 and it's a plain phone with decent sound quality. No camera, no MP3s. It can send texts, but otherwise, that's it. Its battery lasts nearly a week, depending on how much it's used and takes a couple of hours to fully charge.
I got mine last July, and at the time, Virgin had the cheapest rates, but all the "cheap" providers (Virgin, Solo, Koodo, and Fido) offer roughly the same deals.
The only thing I don't like about Virgin is their whole "Hey Dude" attitude and the flirty voice mail chick. I hate it when huge, faceless companies try to act like they're your buddy.