Austin is cheaper than Philly but not by that much since it became a hotspot. (Two radically different areas of the country????) I wouldn't think you could do that home for under 300K anywhere, and 450K or so would be more realistic for a urban area with medium level finishes. Your choice of builder will determine a lot, but there aren't a lot of them out there with the attention to detail and skill to build a truly modern home like this. It's a LOT harder to construct than a similar "traditional" style home because the simplicity of detail doesn't leave any room for crappy work to not show. A traditional home has a lot more wiggle room for hiding crappy work.

FWIW - my father had a 2,400 sq. ft. home built in the greater Austin area two years ago. It was one of the builder's standard plans that had some minor customizations made to it. Build quality was decent, but trim and finishes were very basic (i.e., cheap tile, lower end appliances, carpet, basic plumbing and electrical fixtures).

Cost was about $115/sq. ft not including land. However, the market has heated up since then and many contractors appear to be busy. So, prices have likely gone up.

100-110 in Oklahoma gets a nice home

Depends on what part of Oklahoma you are from. I'm from NW OK and it's higher here.

And I'm curious to know why the OP considers quartz a medium level finish. In looking for my finishes, quartz is one of the higher countertop surfaces.

It's what I see here in Austin homes of that size/style. Entry level quartz sells for about $50/sf at Costco, about the same as Granite. We also have million dollar homes with Quartz here but not the same that you'd find in those homes (and a lot more of it since they're much bigger).

Basic Chinese or Korean quartz that's fairly plain may sell for $50 a square foot, but most of it is in the $80-$120 a square foot range depending on color and movement and what edge treatement and other upgrades you choose.

Brand is CasesarStone from Costco for 2cm Group A at $57/sf in Austin. Yes there are lots of upgrades and install isn't included but that's why I said "medium". Quartz but very low end selection for medium build. I would be ok with a lot of other things tough too, like recycled glass or anything else that fits modern.

I mentioned Philly because my wife and I are considering moving there in a few years since she's from the area. Tear downs in nice areas cost about $300k - $350k right now though so I've been trying to run some numbers to see what it would cost to put a small-ish home in an area like that. Appraisal makes me nervous though. After spending $350k on a lot and then $400k on a building for it, perhaps even low end, we'd be at $300/sf. That'd mean negative equity around there, right? I'd guess we'd appraise around $250/sf or be upside down by about $100k. I guess that's why there's no tear downs there under $1mil?

The only cost estimate that means anything at all is the one on a builder's contract for construction. Even then, one has to carefully review to see what's included, what the quality is for included items/work, and what's excluded.

Often, the area requiring greatest review may be the allowances in a construction contract. Usually, the fewer the allowances, the clearer the final result will be.

As to real estate in the Philly area, it all depends on where one looks. Like every place else, there are desirable areas and undesirable areas. And also like almost everywhere else, new construction may be more expensive per SF than existing housing stock. A tear down and rebuild may be the most expensive option of all, since one is purchasing an improved property to tear down. Vacant land would be less expensive, as would remodeling an existing property. Different strokes for everyone!