What are you gonna contract out and what are you going to do yourself?
Definitely the concrete flat work; I'm lousy on finishing slabs. Maybe the footings and walls too. If we elect to pour the footers and walls ourselves, we will contract the excavation work from a guy that we have worked with before. He already has all the equipment, works by the hour at a reasonable rate, and is cheaper (and more convenient) in the long haul than renting DIY excavation equipment. - Past that, its D-ski and me against the world.