RadioShack has a very nicely integrated product section dedicated soley to Sirius Satellite Radio. The integration of Sirius' content into RadioShack's site is really very well done. Just click through on the links from this page and you'll see what I mean. It links to pretty much everything you'd want to know about satellite radio and Sirius in general - all within the RadioShack site.

Really quite impressive. 

[RadioShack.com Sirius Store]