Construction is pretty much always like that, because the people you have do the work buy materials from someone who gets them from the actual place - so you're paying for labor and a bunch of middlemen. Plus since their work tends to be sporadic you pay for that too - and it just ends up at massive, massive markup. Reading about the actual costs of building a house, you end up paying like 10-20% in materials and the rest is labor, permits, equimpment, (markup!!) and the contractor/overseer. It's pretty mind boggling! I'm trying to learn to do as much as possible myself.