Have you heard of Freecycle?
I realize this isn't a money saving idea, because the whole idea of Freecycle is to list something to GIVE AWAY. I don't have room to keep things around until I have enough for a yard sale, so I post it on Freecycle. It feels good to help someone else out, who may or not be less fortunate than I. In any case, I can get rid of useful items, and at no cost to me, monetarily or otherwise. (yard sales are a lot of work!) Check out your browser for a local freecycle site and go for it!