Ok...let's see what I've learned.
Base Layer - synthetic, wicking, not cotton - check, already have that (Bass Pro PolarTec XPS brand...just the right amount of warmth and extremely comfy)

Outer Layer- water proof preferably, not so much for insulation but perhaps windproof - Check, already have a pair of Frogg Toggs- durability is questionable though. Remember I'm in Texas...everything pricks you, sticks you or bites you. Lots of cactus where I go, often off the beaten path.

Mid Layer- this is where I falter. I need rugged pants to deal with scrub and cactus. I like the idea of the Air Force pants, although you're right about finding them. Should be durable...and cheap...style? Who cares about that, I'm on trail <img src="/forums/images/graemlins/wink.gif" alt="" />
I like the idea of the PolarTec thermals coupled with the 200 wt. fleece...good for days when I'm totally on the path, sounds warm too...off trail though would collect thorns, scrub, etc. like nobodys business <img src="/forums/images/graemlins/shocked.gif" alt="" />
The Wal-Mart/Burlington/Marshall's choice of cheap wind pants over thermals is probably the cheapest and might just work. I used to do that when in college for everyday wear on really cold days...need to look into that. That should be durable, warm if it has a poly liner, somewhat water repellant, and cheap. I just don't want elastic cuffs at the bottom, but I guess those could be taken out.
Hhmmmm...lots of food for thought. This is all good stuff, thank you all very much! Anyone else feel free to chime in!