Door knobs are not generally worth a lot of money, but there are exceptions. Antique door knobs can be quite valuable, especially if they are made of rare materials or have an intricate design. Door knobs that are part of a set (i.e. two matching doorknobs for a double door) can also be more valuable than a single knob. If you think you might have an antique or particularly valuable door knob, it's best to consult with an antiques expert to get an accurate appraisal.