Find your local consignment store and get acquainted! I found a fantastic one nearby and when the kids grow out of there current clothes I bring them in to sell on consignment (in good shape, of course). The best part is, when they need new clothes I shop there and just use my account from things I've sold. Don't have to spend a dime! Its also a wonderful way to recycle. My store has a great woman's section as well.
There are some wonderful furnture consignment stores out there too.