The Salvation Army Thrift Shop isn't one that immediately comes to mind when thinking 2nd hand, but it's worth trying to remember. They have a good selection of clothes for everyone, and lots of other fun stuff to go through. They have more reasonable prices than Goodwill and the people there are pretty friendly.
It is kind of dark and loaded with junk, but that's the only way to go treasure hunting. And they are alway so good to my son. He got 3 little dolls for free in this bucket they have by the counter.
It's a regular stop for me now.