26 C.F.R. § 25.2512-1
Section 2512 provides that if a gift is made in property, its value at the date of the gift shall be considered the amount of the gift. The value of the property is the price at which such property would change hands between a willing buyer and a willing seller, neither being under any compulsion to buy or to sell, and both having reasonable knowledge of relevant facts. The value of a particular item of property is not the price that a forced sale of the property would produce. Nor is the fair market value of an item of property the sale price in a market other than that in which such item is most commonly sold to the public, taking into account the location of the item wherever appropriate. Thus, in the case of an item of property made the subject of a gift, which is generally obtained by the public in the retail market, the fair market value of such an item of property is the price at which the item or a comparable item would be sold at retail. For example, the value of an automobile (an article generally obtained by the public in the retail market) which is the subject of a gift, is the price for which an automobile of the same or approximately the same description, make, model, age, condition, etc., could be purchased by a member of the general public and not the price for which the particular automobile of the donor would be purchased by a dealer in used automobiles. Examples of items of property which are generally sold to the public at retail may be found in § 25.2512-6 . The value is generally to be determined by ascertaining as a basis the fair market value at the time of the gift of each unit of the property. For example, in the case of shares of stocks or bonds, such unit of property is generally a share or a bond. Property shall not be returned at the value at which it is assessed for local tax purposes unless that value represents the fair market value thereof on the date of the gift. All relevant facts and elements of value as of the time of the gift shall be considered. Where the subject of a gift is an interest in a business, the value of items of property in the inventory of the business generally should be reflected in the value of the business. For valuation of interests in businesses, see § 25.2512-3 . See § 25.2512-2 and §§ 25.2512-4 through 25.2512-6 for further information concerning the valuation of other particular kinds of property. See § 25.2702-6 for an adjustment to the total amount of an individual's taxable gifts where the individual's current taxable gifts include the transfer of certain interests in trust that were previously valued under the provisions of section 2702.
26 C.F.R. §25.2512-1