It really depends upon what its worth compared to the comps. The appraisal may have been overly conservative. Sometimes a property is relatively rare and there just arent good comps for it. I had that happen last week in Murrietta on a listing for a 1 story on an 19,000 sq ft lot in a neighborhood of homes like that. There werent good recent comps so they went to the neighborhood next door and tried to use a 2 story on a 6,000 sq ft lot as a comp. I told the U/W to go F^%&*^K himself. They ordered an appraisal review, saw what I was talking about and resolved the issue in my favor. It doesnt always work that way even though it should.
With that said, by closing in the next month you will get an $8,000 1st time homebuyer credit from Uncle Sam which you might not get on the enxt property. Without intiminate knowledge of the property its hard to say but it could easily be worth going forward due to the $8K credit.
At that price they will likely have no problem finding someone else to step up.