Funny you should ask.
We're in the process of exploring an earth-sheltered home, and there are several ways to those as well. Poured, block, and shotcrete.
In our area, by far the biggest expense is the labor. That shoots blocks right away, as they are very labor intensive.
The poured walls can go very quickly if the concrete contractor uses portable forms, but that's not always the case. If they have to build the forms, then you will spend as much on the forms as you will on the concrete and steel.
A new variation on the poured walls is to use the styrofoam forms. These stay in place after the pour and contribute to insualtion. Only problem I've seen is when the pour "blows out" the foam. That is one major mess.
I was talking this over with friend in the construction business, and he told me the newest method is to put up the steel (rebar) for a "standard" poured wall, and instead of pouring, they use shotcrete. No forms. I have never seen one of these, but he'd just finished doing an 18,000 sq ft. house (2 stories above ground, and the basement done the shotcrete way). He said the basement portion of this house only took two weeks.