Lots of choices out there. just read the labels. lots of "sport" pants are nylon, or polyester or nylon/spandex.

Browsing through wal-mart you can find a good selection of nylon or polyester pants..

In my local thrift store there are lots of "track pants" - often just nylon shells. those work good. there is also often a good selection of polyester or wool dress pants - don't discount these! they work good too (although while wool is warm it doesn't dry as fast).

Alternatively REI or your favorite hiking store will have lots of nylon hiking pants, and convertible pants/shorts.

At the higher end there's the schoeller dyneema and fancy mountaineering fabrics - these are generally tougher thicker synthetics. they're pricy though.

In a nutshell, look at labels, you can get away with anything from cheap wal-mart pants, 5 or 10 dollar thrift store pants, or 120 dollar schoellers...

Think a little bit about where you'll be, and how fast what you're holding is likely to dry...