An independent appraisal may cost some money(typically 300-400), but it is a great way to get your value. Do not have it done as part of a refinance(they are typically inflated) It is also accepted by lenders as the value, and can be used in marketing if you decide to list your home(e.g apraised for 300k, asking 295k). Appraisals are generally good for 6 mos.
Right now many buyers are nervous about overpaying, give them a reason to feel comfortable. If you add the appraisal with the CMA's suggested by Beth, I think you'll have the best assessment of your home's value.