The subject of "market value" is closely connected with hearsay, in that, in the usual routine of business, merchants, commission men and brokers, are wont to rely upon market and stock quotations and reports of sales, or sales, a knowledge of which they have obtained by hearsay. Real estate brokers daily base their estimates or opinions on reported sales or reports of income derived therefrom. While such sales or income cannot be proved by such reports, or by market or stock quotations, yet such sales having been proved by eye witnesses having competent knowledge thereof, opinions of experts based thereon are admissible to prove market value, and to say whether or not such transactions represented the true market value.

In actions for breach of contract for goods sold, and not delivered, or not accepted, the market value of the goods at the time and place of delivery must be shown.