I'm on the $30 plan and the One doesn't even show up on the list of phones I can choose from (even after going through the One page and clicking the "already a customer" link). This is lame.
So I got an email from HTC with a link to their page with the drop down tool. Played around with it and looks like any phone on their list is estimated at $100. I have an old EVO 4G that I flashed over to Boost that I'm going to dig up and turn in if that's for real.
Facebook
Twitter
Instagram