How have the courts treated expert opinions on the value of a property?

It often happens, as in this case, that the experts know of few, if any, comparable sales in the area for such purposes. That circumstance, however, when called to the attention of the trier of fact goes to the weight to be accorded the experts' opinion rather than its admissibility. As stated in La Macchia, supra, 'It is clear that one who has given his opinion as to the value of certain property may, upon direct examination, state the reasons upon which it rests. Long Beach City High School Dist. of Los Angeles County v. Stewart, 30 Cal.2d 763, 773, 185 P.2d 585, 173 A.L.R. 249. But the facts stated as reasons do not become evidence in the sense that they have independent probative value upon the issue as to market value. [Citations] Instead, they serve only to reinforce the judgment of the witness, that is, they go to the weight to be accorded his opinion. * * *