The appraisal of any real estate is, of course, merely an expression of opinion, and the only true measure of its value at a given time is an actual sale, or a bona fide offer of cash or its equivalent. At the same time, before passing such an entry as that described, an accountant should satisfy himself that the property taken on the books, to the best of the information obtainable by him, is taken at a fair valuation. This valuation, of course, should never exceed the price actually paid for the property. In other words, if an owner takes property in exchange and allows $1,000 for it, it should be entered at this figure even if he considers it worth $1,500. The excess of $500 should not be put on the books until an actual sale of the property has proved that such value exists.