I have two. One came from Poserworld, the other from Daz. The Daz one has track pants and casual pants in the same folder.

http://www.daz3d.com/i/3d-models/-/m3-casual-clothes?item=1665&_m=d

Poserworld is $30 for 3 months but you can download everything they have if you have time. They also sell content cds.