Remember, an appraisal is just an estimate of value based on recent sales comparables in your neighborhood. The only way you truly know the actual value of your home is to find out what a Buyer is willing to pay for it (ie. via a Listing).
I suggest getting a Competitive Market Analysis (CMA) from a local Realtor. That should be as good as an appraisal (and free) for what your seeking. Otherwise, you can do your own research and find out what similar properties in your neighborhood are being listed at for sale.
Many folks believe that the taxable value as indicated by your local Tax Assessor is your appraised value and that is not necessarily true.
Hope this helps.