$62 for the Delphi SkyFi receiver, $70 for the car kit (but it actually only cost me $20 because I had a $50 Best Buy gift card, which is part of the reason I went this route), $60 for the adapter, and $12 for the cradle. That's $204 if you count the full price of the car kit, but it only cost me $154 because of the gift card. There's also the fact that the adapter is neat because I can now hook up an mp3 player or anything else (CD changer, etc.) through the head unit. There's also the fact that my XM receiver can be used outside the car as well.
So anyway, it was significantly cheaper for me (over $100), and I liked the setup better anyway. If you wanted it to run through the head unit and don't care about being able to get XM outside the car, though, yea, it's probably better to go with the factory XM setup.
I have seen XM reciever in the local Best Buy for less then $60. Do you think that will still work. My bro has it with his XM Commander and it worked on his mazda 6 and i'm not sure if it's going ot work on the tc. I read somewhere that you need some adaptor to be able to attach the reciever or something.
Let me know if you're still interested in XM. I'm selling the factory setup - everything needed for a Scion. I got it about 90 days ago and everything works perfectly. There's also a much easier installation than recommended by the factory. This includes the XM tuner, cables, antenna.