Hi Tom,
I agree with Christopher, Those aren't good comps. You would want your comps to be closer to size as the subject property, particularly the heated sq ft. Even with the adjustment being made for the differences in sq. ft, sometimes for the comps that are much bigger, adjustments would have to be made elsewhere. For instance. comp 7 and 8 is drastically off and comp 7 is an entire house bigger than comp 8. I also personally believe that when all those comps are being used, numbers start getting skewed.
I also agree with Christopher regarding your options for buyers on the FHA loan, however, I've had a buyer utilizing a conventional loan with 40% down and we had a similar appraisal issue where those same options applied to him. They didn't have to pay the difference out of pocket due to the large downpayment, however, they refused to purchase an overpriced property. I make sure that all of my buyers sign an appraisal contingency, so we were able to negotiate the price a bit. With that being said, whether the buyer is using an FHA or not, the same issue may come up with a buyer on a conventional loan.
One note, a buyer on an FHA loan will most likely not be able to pay the difference out of pocket, so you're down to two options, find another buyer who will or lower the price.