This is kind of like asking a car dealer, “…what does a car cost?” How big of a car, how powerful, what kind of handling, what kind of fuel economy, what residual resale value, what kind of upkeep/maintenance? There are certain factors that skyrocket building costs – commercial kitchen appliances, bathrooms with spas and steam rooms/saunas, radiant heated floors, bidets, fiberglass tub shower enclosures versus customized granite slab/tile utilizing frame less glass panel enclosures, swimming pools with cabanas, colored concrete stamped decking, composite decking materials, tile roofing with copper gutters.
Electric wiring employing auxiliary generator circuits, multi lighting circuits with dimming capability, future capacity for possible equipment, task lighting, art feature lighting, outdoor lighting, automatic scene lighting, music distribution systems, home video/theatre rooms can add dollars.
Plumbing utilizing on demand water heaters, recirculation pump loops for hot and cold distribution, fire suppression systems, sound deadening piping for waste water systems can eat up finances.
Energy systems using insulation air sealing spray on foam products coupled with blowing fiberglass blankets (hy-brid), high performance windows using argon gas, or heat mirror materials along with frame materials, different efficiency of heating cooling plants, and various methods of distribution of the energy. Landscape waterfall features and automatic moisture sensing irrigation systems all need to be regarded over the life of payback on savings.