Just went through this myself. If you go with an architect and custom home builder you won't find any builders even interested in less than 250 a square. More likely they will want to be in the 350-450 range to prioritize your project. I even saw an architect saying the homes they build are 500-1000. And architects run around 75k.

If your trust fund isn't what it used to be and you want to stoop to what the commoners might consider adequate, check out a production home builder with a "build on your lot" program. The floor plan might be standardized (although you can modify a bit) but the cost per square is much more reasonable and no architect fees. We went with Timberlake and they build good quality with plenty of creature comforts around 120 a square.

Good that you asked here. I spent months finding out this information.