Another thing to keep in mind is the cost of the land. Brookfield purchased the serenity lots at the peak of the bubble in the 500k range. Post bubble prices for stonebridge lots averaged 350k.
This is why similar sized cityventure viscaya homes backing to steep slope like the serenity home you are interested in ended up going for the high 700k range. Toll bros also has this advantage compared to serenity as they also purchased their lots at the post bubble 350k price. Hopefully this will be translated to their asking price just like cityventure.