Price, in my experience, for a new house is going to vary based on a
number of factors.

In the Charleston SC area, $150 to $100 per square foot is usual.
This depends on location for the same house.
I'm not including some of the super upscale gated communities.

One story houses are a bit cheaper than two story houses

Slab on grade is a bit cheaper than crawl space and a lot cheaper than
basement.
Basements are rare because of drainage, and water table height.

It strikes me as important that your wife chose a 1600 square foot
house as larger than your 2000 square foot house. My first assumption
is that there is a need / want to use space differently than your
present layout. What does your wife want the extra space for?

I suggest, as I do to all my clients, that you reach a consensus on the
way you want a house arranged. Walk through your house and talk about
what you each like and don't like as a start. You don't want to
draw anything until you have an agreed upon overall idea of what you
want.

Tom Baker