Goodwill and Salvation Army are crazy. Our Goodwill actually went out of business a few years ago, then came back in a different location with even worse prices. The Salvation Army may have better prices, but it's so dirty and smells so bad I don't even try anymore.
We have a great, local store that has a 0.50 color tag every week, then marks whatever is left down to 0.25 the next week. I find great stuff for the kids that way and work clothes for me (messy lab work, the cheaper the better). They get a little ridiculous on housewares and furniture sometimes.
We also have a twice yearly kids consignment sale, but it's hit or miss. Every sale the lady that runs it sends out these scathing emails reminding people to price their items appropriately (ie 1.00 per piece for wal-mart and target brands unless they're new, take into account wear and tear, etc). People still price some things way too high, so many things are nearly worn out and priced at retail. I usually wait and go to the last day when everything is marked 50% off.