Sec. 9. (a) A claimant occupying real property who has color of title may recover the value of lasting improvements to the real property made by the party under whom the claimant claims, as well as those improvements made by the occupying claimant.
(b) A person holding the premises as a purchaser, by an agreement in writing from the party having color of title, is entitled to the remedy set forth in subsection (a).