True. But if they negotiated to a different price, there might be reason for a new opinion of MV
That might be true IF the physical characteristics of the subject's site or site improvements changed. IF not - zero reason for OMV to change. MV is determined by the competitive market - OTHER buyers of OTHER properties which would serve as substitutes for a subject's real property.
The CP$ is totally irrelevant as it reflects only the hopes, dreams, goals, and aspirations of ONLY a particular buyer and a particular seller - NOT the competitive market. A purchase price may, or may not be competitive due to specific motivations of parties with vested interests in "doing the deal".
It may or may not be supported by the Competitive Market. Determining same is the primary reason for an INDEPENDENT, and wholly Objective (not subjective) Opinion of Competitive Market Value.
The other is for a Lender to have a compliance document - and an Appraisers' E & O insurance policy to target when the loan defaults because they floated a loan to people who could fog a mirror without adequate financial qualification.
Whether a contract exists, or not is irrelevant to Market Value. Regardless of who the seller, buy, or lender may be - OR the purpose of an appraisal (loan, trust, estate, bankruptcy, divorce etc.) - MV is demonstrated by the Competitive Market - NOT an Active Listing, a Contracted Listing or a Purchase Contract ALL of which are
not yet confirmed by the competitivemarket and are mutable prior to closing.