Legal Question in Real Estate Law in California

You could hire a qualified appraiser or, if it is real estate, do what appraisers iln fact do. Look up all the sales in the general area, find out the size, etc. of each similar property, factor in the changes in the economy, and guess.

You can get a ballpark number from zillow.com. Depending on the locale they have anywhere from a 10% to 40% margin of error. Many real estate agents will also give an estimated market value for free. If you want a "real" number, you would have to hire an appraiser, but as Mr. Shers says, even that is a guess, a highly educated, experienced and trained guess, otherwise known as an estimate.