First, value estimates on Trulia, Zillow or anywhere else are not reliable for making any decisions. They are estimates slightly better than a dart thrown on a dart board. Next, all valuations must be based on the local factors. A home like yours that sells in San Francisco will go for a different amount than if you are in Oakland or San Jose. All real estate is local based on supply, demand, economic and employment factors. A professional appraiser will rely on the most recent sales of the most similar homes in the closest proximity to the subject property.