Question about UFO calipers

[Kevin Rufino]

I was checking my brake pads this past weekend and noticed that the 
outer pad on the passenger side was much thicker than the other three 
front pads.  I ran this by a gear-head friend (I am a car novice), and 
he said that it sounds like the caliper carrier is stuck or binding.  I 
checked all of the Audi parts sites that I usually use and none of them 
list a caliper carrier, nor a full caliper for UFO brakes.  Does anyone 
know where I can get a carrier, or a full caliper (which ever would be 
cheaper)?  Does Audi still carry these?  Is used my only recourse?  Any 
help would be greatly appreciated.

Kevin