I actually saw your listing on MLS. The grounds and perennials are beautiful, and the interior photos are very nice, but it appears that your property is significantly overpriced. Mind you, I am basing this solely on MLS stats and I have not personally seen your home, but your asking price is the highest per square foot for living area of all homes currently listed in Rockport between $500K and $675K.
My humble opinion: if you want to sell your home by August, list it for what you paid for it in 2006 (at the height of the market) at $499K. Unless you have done significant work to the property since you purchased it, it hasn't gone up in value. Good luck.