Gameday audio subscription is $20 for the year (I think). I've bought MLB.tv the last 2 seasons which comes with the audio package included, so I can watch games on my PS3/Roku when I get off work. The MLB At Bat app for iPhone and Android include audio, but I'm pretty certain it only works on the phone and not for the site/archives.
By the way, are we . . . I mean . . . you getting that again this year?