You know what? Cindi is correct! And I'm embarrassed that I forgot to mention anything about this.
Please bear in mind that certain upgrades really must be done when a home is built, like an extra row (or even 2) of blocks in the basement, or extra recessed lights, etc. Lots of other stuff can be done later, and for much less if you do it yourself or even just with a decent handyman or contractor.
The only upgrades that we wished that we HAD done and did not were more recessed lights in the kitchen area.
If you do proceed with new construction, you'd be well-advised to get a radiant barrier installed after it's built in the attic. This will cost about $500 to do yourself, and it will save you at least double that every year in heating/cooling.