Why is the appraisal higher than what a buyer offers?
Replacement value is what a shop charges to sell you the piece new. A buyer pays what they can resell it for which is usually a fraction of that.
Three different numbers
Replacement value is the retail price of an equivalent new piece. It is the highest of the three and it is the one insurers want.
Fair market value is what it would change hands for between a willing buyer and a willing seller neither under pressure. Estates, divorce and tax use this.
Quick-sale value is what a buyer pays this week. It is the lowest and it is why a $14,000 appraisal can turn into a $3,000 offer at a counter.
Ask which value they are writing
An appraisal that says $14,000 and an offer of $3,000 can both be honest. Ask the appraiser which value they are writing and say what you need it for.