YOUR BUDGET DETERMINES EVERYTHING
Have you noticed how much variability is seen in construction "costs?" Variability most likely will never change. The reasons for these variations are vast. There are different levels of every facet of a construction project - materials, skill level of trades, level of design (or lack of), knowledge of general contractor, the professionalism of the company. Naturally, finer features will correlate to a greater overall project cost. The annual cost guideline put out by Remodeling Magazine, Cost vs. Value (See Link Below) has average costs for various projects that are constructed by professional, licensed general contractors doing permitted jobs.
For new construction projects, people like to talk in terms of cost per square foot. That can be helpful in general, but it really depends on how 'custom' your project is. If you will be tearing down a house and preparing the lot, that will also factor into the overall cost. The larger the house, the lower the square foot cost will typically be. If cost is the determining factor, it is best to start with a budget and work backwards.