An appraisal is a tool and an opinion like anything else, but fixed to that moment in time. It is not a guarantee that a home will sell for that amount. What if, 3 days after the appraisal is complete, 2 more comparable homes sold within the radius of the subject home that had a significantly different (higher or lower) price than the previous comps? I had a listing where the appraisal said was valued at $317,000, we priced it right around that price... but it sold a year later for significantly less than that after we had to reduce the price. Even a CMA is only good for a snapshot of that moment in time - it's a starting point, not the ending point.