I'll second Sierra Trading Post...If you've ever been to Ross, Marshalls, etc., it's like that for outdoor gear, but you can pick up some awesome deals. Sign up for the e-mails, they actually send some useful discount codes.
I got sets of merino wool socks, with liners and heavy out socks, that were originally $25 a set, for $5 a set.
You just have to check into the website regularly...they had some nice Carhartt polypro stuff last year, but I didn't want to spend the extra money at the time ($15 apiece), now they're gone and I'm kicking myself in the butt for not getting it.