I've posted this up before on other threads, but...Target C9 Golf Pants - offered in variety of drab colors, durable, lightweight (9.5 ounces), dries lightning quick. Oh, buy 4 pairs and they are a whopping $23 each. Best September elk hunting pants I know of...
Alternately, Sierra Trading Post occasionally runs a special on Reddington ReCharge Pants for $21.49. Cheaper than the C9s, feel a little cheaper made, but weigh in at 8 ounces. Also offered in some great solid drab colors.
For a very lightweight conscious hunter that thinks camo is WAY overrated, either of these options will let you hunt cheaper, lighter, and just as effectively.