the most you can have for xbl is 36 months prepaid, according to xbl.
the other option being, you get the messanger kit and split the contents with someone you know. there's always someone who needs an extension to their XBL account, a newer headset, and/or PGR game.
otherwise, wait...with twitter and FB on XBL, there should be an influx of both aftermarket and new chat pads coming soon. hopefully they make them in black and red.