Caught this over at FatWallet.com. Looks to be good for SERO users as well. Wasn't sure where to post it. Mods, move if need be.
http://sprint.com/citigroup
Click upgrade your phone from an existing account, enter your login information, choose your number if you have multiple lines, then follow the checkout process. To get these prices you of course have a 2 year contract extension.
Free shipping, free activation.