lightspeed has a great trade up program as well. I have an old thirty-3g and will end up trading it for the zulu at a significant discount. great company. you can get a new headset every few years the rest of your life for a couple hundred bucks.....
I have a 30-3G as well, and I got it by trading up my 25XL plus $200.
There is nothing on their website about trading up to the Zulu yet...do you know something I don't?