I managed a construction office for both Commercial Builders and a high end residential builder. These cocts vary widely based on the cost of the lot and the finishout selections. For example Formica kitchen counters are cheap between $20-40PSF, but if you choose Green materials (concrete, recycled glass, etc.) it will cost more in the $50-80PSF range, if you choose a high quality solid granite or natural stone you could be paying $50-200 per square foot plus installation costs. You could install $15 can lights or opt for a $3000 light fixture. So it all depends on who is building the house. There is not correct answer.