SD R can probably comment better on this one but it looks to have sold about $50K below market. I didnt see the house and dont know if there were problems with it but that does not appear to be the case in any comments on the listing. It was a short sale and the listing agent appears to have snuck their buyer (who also got a $5K credit) into the deal. There looks to have been only one loan for about $520K so it was the perfect opportunity to sneak on these through as even if they got $550K the seller would get nothing so they wouldnt care and the loss was small enough it wouldnt be highly scrutinized.
With that said there are more buyers on this board alone looking in PQ for deals like that than there are deals like that. Throw in the universe of buyers looking for deals and one would have to be pretty fortunate to scoop up somehting like that at that price.