I understand that, and that's the problem - there's only 1 or 2 on there, and the price is way high compared to the rest of the set because it's exploited...because it's not given as a quest reward. This would be fine if the set items given from a related quest was random, since then all items in the set would be constantly traded for cheap, but unfortunately the devs put each set item as a specific quest reward and left out the pants; this is likely not intended, which is why I'm labeling it a bug.