Right now,
www.xmradio.com has their Roady2 model on sale for $29.99! It's a complete package; nothing more to buy. Installation is straight forward.
The only option I'd get is the kit that taps into the antenna wire, so that the sound will be better quality. I believe it's another $29.99. But, this kit is highly unnecessary. The Roady2 sounds pretty good, as is.
I have the Roady2 installed in my wife's Escape. After I got my HAH, she started to enjoy having XM when in my car. So one day, I surprised her by installing XM in her Escape! She loves it.