What To Look For
Before you purchase hiking pants, ask yourself what sort of conditions you'll be hiking in. More than anything else, this will dictate what sort of specific product you'll look for.
If you expect to hike in dry, hot conditions such as those found in the southwestern United States, for example, you'll want to purchase lightweight, breathable fabrics that provide adequate ventilation and help wick moisture away from your skin.
If you're hiking in the Pacific Northwest, on the other hand, you'll want a product that is waterproof and windproof to help protect against the relatively damp, gusty weather you're likely to encounter. Seasonal weather will dictate your hiking pants buying needs also; for example, winter hiking pants should have built-in gaiters to help keep snow out, which is a much less critical need for summer hiking pants.
Zip-off legs are a common feature in hiking pants and are useful if you expect to hike in widely varied conditions; otherwise, you might as well stick with either shorts or pants and save yourself money.
Other features that may be worth your hard-earned money if appropriate to local conditions include: Sunscreen/sunblock ratings up to UPF 50, bug repellent coatings, ventilation zips (often located on the thighs) and calf-zippers to make getting your pants on and off over boots relatively easy.
Common Pitfalls
The biggest problems to watch out for when purchasing hiking pants are poor fit and poor construction. Hiking pants must fit well not just in the store under controlled conditions but also outside under heavy use. If they start chafing your legs after a few miles, odds are good that you will never put them on again. Similarly, if you can't wear your hiking pants comfortably without extra layers underneath--or if you can't squeeze into them and move easily with thermal underwear on beneath--they're not going to be very useful in the varied conditions you encounter outside.
You should also expect your hiking pants to perform well in sand, mud, dirt, rain, heat and wind. Common signs that they may not stand up to these "poor construction" tests include frayed or loose seams, difficult or broken zippers, missing buttons and premature scuffing in the fabric.
Where To Buy
Hiking pants of various configurations are common wares in almost any outdoor products retail shops including REI and Cabela's. If you're looking for the best deals possible, discount retail websites like Mountain Gear, Sierra Trading Post and Campmor may have what you need. Sporting goods stores are less likely to carry summer hiking pants, but they might--and they're usually an excellent source for skiing and snowboarding pants, which often make the best winter hiking pants possible.
Cost
It's not unusual to find hiking pants for adults at a retail cost of anywhere from $60 to $100, with kids' hiking pants costing between 20 and 40 percent less than adult sizes. If you're diligent--shopping online bargain sites or scoring big at retail store clearance sales--you can usually track down hiking pants for as little as $20, but this takes a lot of patience.