This is the best place in the city to sell your used (but still trendy) clothes and get some decent money back for them. There have a few stores around San Francisco but my favorite is the one on Fillmore. You may have to dig a little, but you may come up with something awesome! This store sells some used designer names at cut rate prices as well as good basics. Just make sure to avoid the weekend, because that's when it's busiest and everything gets picked through.