I am always on the look out for new hardware, whether or not I actually have a project in mind. So much so that I carry a screwdriver around in my purse. Some of my favorite hardware has come off of the abandoned furniture from the streets of San Francisco. When thrifting remember to not just looking at the furniture but to check out the hardware, if the furniture item isn't great but is a good price I will buy the item for the drawer pulls or knobs.
Another great place to find unique hardware is at the Alameda Point Antique Faire, there are a few vendors that have a small selection but there is one gentleman that has an entire booth dedicated to vintage treasures! I have also found some wonderful pieces at many of the San Francisco thrift stores, Community Thrift and The Salvation Army in the Mission have a lot of furniture turnover so if you see something you like you have to get it when you see it or it won't be there tomorrow.