The most inexpensive home to build is tract home by a production builder, on their lot. They build on a scale that isn’t reproducible with a one off project. So the one off project is always going to be more than a tract home in a subdivision. 1st strike against a budget.

A large home is more expensive than a small home. But a small nice home will be more expensive per square foot because you can’t build a house without a kitchen or bathroom or HVAC or windows. There’s a certain base cost for everything. Beyond that, adding square feet isn't that costly. The trick is to not let the guts of the home get so large that it costs more to maintain, yet not get so small that the rooms have to do quadruple functions. Triple functions is fine. A guest room/exercise room/home office is a great combo. A stand alone home theater is not wise $$ spent. A 30x24 kitchen is a sick joke to a “budget build“, yet I’ve seen people who have that, and want to know why the cabinets are 120K. Because that’s the size of 6 standard 10x12 kitchens is why!!

A complex, fat house, with lots of gables and roof jogs is more expensive than a simple single plane ranch house. But that’s to a point too. People gets stupid nuts about simplifying an exterior form and take it to the illogical extreme as much as the crowd that wants to “add interest” by tacking on another material and another bump out. A simple house need not be severe. Adding a cross gabled wing that makes architectural sense won’t break anyone’s budget.

Those large begabled monstrous fat garages with added on little houses are a symptom of the thing that will REALLY cost you money: bad design. Bad design has cost home builders billions. Not siting a home to work WITH the property costs in added energy use, and in site grading or fill. It makes for a less pleasant house, which had its own costs. Build what you need, and no more. And make that function beautiful, with the help of the right architect. And your bank account will rejoice.