No. Truly accurate cost-to-build estimates should come straight from your local builder. Relying on a “seat of the pants’ online cost-to-build estimate is risky. They may be cheap at $25 dollars or so, but are wildly inaccurate.
To get an accurate estimate for your area we strongly recommend speaking with a couple local builders and/or real estate agents who specialize in new construction. They will factor in local labor cost (a huge factor!) and local material supply cost.
Regarding choosing a design, generally speaking the more corners in a design, the more expensive it will be to build. Other design factors that impact cost:
1) One and one half story homes are generally less expensive to build than one story or two-story homes (more square footage – less siding material).
2) The larger the footprint, the more the design will cost to build per square foot.
3) Your material choices (high-end windows vs. builder grade windows; granite vs. Formica; metal roof vs. asphalt shingle roof; heart pine flooring vs. carpet, etc.) will have a huge impact on cost to build.
We have found one online estimator that produces fairly reasonable guesstimates: www.building-cost.net
We still recommend speaking with folks local to where you’ll be building because material and labor costs can vary dramatically from region to region. (For instance: An 8′ 2×4 cost $5.49 in Denver right now, versus $5.98 in Charleston, SC. That’s 10% higher, just for one material).