Testimony of an item's value may be given by either the owner of the property or by a non-owner. See Sullivan v. State, 701 S.W.2d 905, 908 (Tex. Crim. App. 1986). When the proof of value is given by a non-owner, that person must be an expert qualified as to his knowledge of the value of the property and must give testimony explicitly as to the fair market value or replacement value of the property. See id. at 909; see also TEX. R. EVID. 702. The owner, however, need not base his testimony of value on either fair market or replacement value. See Sullivan, 701 S.W.2d at 909. The owner may simply testify in general or commonly understood terms as to his opinion or estimate of the value of the property. See id. Testimony of this nature is an offer of the owner's best knowledge of the value of his property. See id. If the trier of fact accepts this testimony, a reviewing court may not find it legally insufficient as to an item's value. See id. It has even been said, in the context of a challenge to the legally sufficiency of the evidence as to value, that if a defendant wishes to rebut the owner's opinion evidence as to value he must do more than merely impeach the witness' credibility during cross-examination; he must actually offer controverting evidence as to the value of the stolen item. See id.