Generally speaking the price of homes have declined since 2009, some areas in Harborfield more than others, which is typical of most areas of Long Island. Long Island has been a stronger than average market as compared to other areas of the country that have seen more devastating price drops.
I cannot avoid being self serving to point out that the specific details of your query should be addressed to a Realtor. The internet can assist you with general information. My single most important function is to be pinpoint accurate with my numbers. Buyers and sellers depend on my expert opinion when making a decision on the biggest most significant asset they will invest in.