Nothing in this chapter shall prevent a person, after being informed of the right to receive just compensation based on an appraisal of the real property, from making a gift or donation of real property or any part thereof, or any interest therein, or of any compensation paid therefor, to the agency. The agency shall obtain an appraisal of the real property and offer the full amount of just compensation due unless the owner, after being fully informed of such policy, releases the agency from these obligations. An appraisal is not required if the agency determines that an appraisal is unnecessary because the valuation problem is uncomplicated and the fair market value is estimated at two thousand five hundred dollars or less, based on a review of available data.