If the appraised price doesn't seem justified, ask for a second appraisal by a different appraiser (though you or your agent may have to pay for it).

WSJ: Pressured to Cut the Price--WSJ House Talk

Ms. TRAIL ZEA: Twenty percent over the pre-Katrina appraised price.

NPR: Realtors Hash Out Future of New Orleans' Market

Since the financing is based on the lesser of (1) the purchase price or (2) the appraised value, an appraisal that results in a value at or above the contract purchase price means the deal remains intact.

FORBES: Anatomy of a Purchase Mortgage - Chapter Two

Another scenario: The buyer refuses to pay more than the appraised amount and renegotiates the purchase price with the seller.

WSJ: The Appraisal Betrayal | Jumbo Jungle

I. are buying in a nice neighborhood in a great northern New Jersey town was appraised for more than the contract purchase price!

FORBES: Anatomy of a Purchase Mortgage - Chapter Two