What does that have to do with this thread? The OP isn't buying a prebuilt house. Probably because they're not good houses.
I'm sure it varies regionally, but where I'm at (Kansas City market) you have to be in about the $800k range, generally, to be able to work with an actual architect and build something custom - and that's just plain out of reach for most people.
But that's been roughly the way things have always been.
What's changed is the creation of a middle path of "built to sell" homes.