At the Frank Kent(Ft Worth) shows:
Roof-Mounted Luggage Cross Rail Package (Package contains 2 rails, 4 end caps and 4 keys) - 12498492
With Installation: $358.89
Rocker Panel Protector - 12498471
With Installation: $553.70
For more info try
http://www.gmaccessories.net/content_loc.aspx
Sewell is suppose to be coming online soon