backcountry.com (BCA) has great deals and unlimited lifetime warranty. Their in house brand, Stoic is hit and miss. Sometimes it's amazing value sometimes it blows. Good overall.
steepandcheap.com (SAC) is their liquidation web site. Also check their new gear cache.
http://www.sacalerts.com/ to check what was on SAC. While they only offer a 30 return policy, they honor stoic lifetime warranty.
I just scored a 15F 850 fill down 2LB bag for $209 on SAC. Nice bag. Very close to the Western Mountaineering bag I got my GF for more than double the price.
geartrade.com is where SAC sells some of their returns.
theclymb.com good fire sale site.
golite.com is a good manufacturer. Their prices are unbelievably low. The imogene tents, quest backpacks, and Z10 sleeping bags are very nice.
zpacks.com cuben fiber stuff and quilts.
Froogle.com to find the cheappest. BCA is usually at the top.
To find used gear on forums type "fs -article name-" in google.
If you have to carry your stuff make sure you go LIGHT LIGHT LIGHT. Read mike clelland ultralight backpacking tips. The book is filled with great tips on how to lighten your load and how to save money. Sure it gets a bit extreme when they guy recommends using an underrated sleeping bad and doing crunches when you get cold.
If you are backpacking, can I be your personal shopper? I love gear whoring.