Sounds like you are about to buy the most if not one of the most expensive houses in the Tabone subdivision. Is this correct? All the sold comps on the MLS are about $100k below the asking price you have stated so without knowing any specifics about the home or this transaction it is impossible to say what to offer nor am I implying what to offer.
Are you working directly with the builders salesperson? Or do have a buyers agent? I strongly encourage you to get the your own representation whether that be an agent or attorney to protect your interest not only financially but legally.
Quick example on new construction, upgrades and not having your own representation:
A client of mine bought their first home without an agent. It was new construction. They had the choice of a full basement or upgraded kitchen. The builders sales rep failed to tell them they could go back and upgrade the kitchen anytime but adding a basement would be extremely expensive if not impossible. Unfortunately, they chose the upgraded kitchen (the builders sales rep fully supported that choice/gee I wonder why???) and they where one of only a handful of homes in the area without a basement thus making resale difficult.
Have a great day,