A significant proportion of my work is semi-custom and most requests can be met. The building process takes at least 3 months, so some patience is required . Many manufacturers build a lower priced mahogany guitar to use materials that would otherwise be wasted. By using the less desirable woods and eliminating any extra details the final cost is kept down. Unfortunately this results in mahogany guitars looking like the poor cousins while often out performing the more ornate rosewood models.
Time taken to build an instrument is the most important factor, the material costs are less so.
I have never noticed any dramatic difference between a cutaway or non cutaway version of otherwise similar guitars. A cutaway guitar should be chosen because you need it, want it, or the guitar you like has one. Otherwise its neither detrimental or advantageous. Many players never play standing up and don't require buttons. A strap button can complicate the installation of a pickup jack and if the guitar is dropped it may split the tail block.