Valid point. I looked up average materials cost for a 2000 sq ft house and it was estimated at $120k. Materials costs vary much less across the country than land and labor.
For 580k I could hire 2 skilled men and 3 undocumented immigrants for a year.
There's a lot wrong but a lot of it is in your assumptions. For starters there's more than 2 skilled trades that go into a house for starters. Then by hiring them yourself either you or one of those people are going to be playing project manager to make sure they don't run out of materials which is a job in and of itself if you're not familiar with it.
Hey you can play fuck fuck games all day about how 5 person years of labor, almost half of that highly skilled (I'm accounting ~150k+ all in compensation) is not enough for a cookie cutter 2000 sq ft house. I'm calling bullshit; if it really is taking that much for a McClone basic bitch house then someone is taking the piss somewhere.