Parts I bought (at local dealer where I bought my truck)
999U9-AS004 Sirius tuner $215
999U9-VS003 SIGMA antenna $68
999U9-VS006 Tuner pack brackets $20
All in stock.
TOTAL (tax inc) $323.45
Went in pretty quick. I did not remove any of the lower dash trim panels. Only thing I unbolted was the gas pedal assembly.

Mounted it using the brackets, piggy-back on the BCM with included bolts. Solid. PM me if you want a little more detailed procedure on how I did it.
From what I can tell, this is the latest Sirius tuner, it has one antenna jack, so no dorking around with a splitter. Tuner kit comes with a nice bag of installation goodies: velcro, cable ties, tape, foam pads etc, etc. Hanging on to what I don't use for other projects.
Sigma antenna. I was shocked at it's size when I unpacked it (big), but now that it is up, it is very unobtrusive. Mounted it dead-center on the glass in the shaded area above the mirror.
Only thing left is to finish routing antenna wire, and dressing up wires to/from mirror. It was dark out when I got it running, I will clean that up this w/e. I will get a pic up when done for those who are itching to try this.
Got it activated, the sound quality is fantastic. Equal or better than CD. Now I am gonna have to upgrade speakers and get a nice 100w 4 channel amp so I can fully enjoy it!
Yes, it is the more costly way to go. Probably set up a no-frills portable setup for a quarter of the costs.
But it works great, I can just tap the audio button if I want title/artist, a turn of the tuning knob shows the rest of the song/artist name if it is long. I have assigned presets, so I can use the wheel controls for volume and flipping between presets, and jumping between music categories.
I know there are a couple of other guys here thinking about doing this- just go for it!