If you're already a supporter, you can get one, if you didn't get one last time, for $6 USD paypal'd to email@example.com, with your username.
I'm considering opening it up to those who got one the first time to get a 2nd -- there isn't a whole lot of precedent for re-issued supporter items. I *think* I allowed that on CB1 when I re-issued the Glaive of Pain but I don't remember for sure. If you have a convincing argument one way or the other, please share it. :)
Update: okay, veterans will be allowed to purchase a second.
Update 2: this means all supporters can get a RoE during this re-issue period, not that players from before a certain date can get 2 if they didn't get one the first time around