Okla. Stat. tit. 23, § 92

In estimating damages, except as provided by the two following sections, the value of property to a buyer or owner thereof, deprived of its possession, is deemed to be the price at which he might have bought an equivalent thing, in the market nearest to the place where the property ought to have been put into his possession, and at such time after the breach of duty upon which his right to damages is founded as would suffice, with reasonable diligence, for him to make such a purchase.