Date of Death Valuations
Attorneys, accountants, executors and others rely on JAD Appraisal Services, LLC for "date of death" valuations because such appraisals require special expertise and training. They require a firm that's been in the area for some time and can effectively research comparable contemporaneous sales.
Real property isn't like publicly traded stock or other items which don't fluctuate in value very much or for which historical public data is available. You need a professional real estate appraiser, bound by the Uniform Standards of Professional Appraisal Practice (USPAP) for a high degree of confidentiality and professionalism, and you need the kind of quality report and work product taxing authorities and courts need and expect.