The articles of agreement, or the amendment, shall provide for the determination of the value of the property to be acquired in one or more of the following ways:
1. In articles of agreement. A valuation set forth in the articles of agreement or the amendment.
2. Appraisal. By appraisal, in which case, one appraiser shall be appointed by each commissioner, and a third appraiser appointed by the first 2 appraisers.