When we moved to Idaho, we bought an unfinished house (framing, exterior plywood, roofing - and that's about it) and planned to do all the work ourselves. My dad does every construction trade, so over the course of basically 4 years we've done everything ourselves.
A really big part of it, if you're going to do most of the work yourself is time management. Do you have enough time to spend building your house, while injecting materials into it ($), and working whatever your job is? If you don't have much time, it's going to take forever (much longer then you ever think).
I don't know what your skill level is with different trades, but something to keep in mind if 50% of the budget is going to other subs, is what trade you're subbing out. If you can do some of the more specialty custom stuff yourself (trim, tilework, countertop and masonry etc...) and sub out horrible time consuming crap like drywall (which is relatively cheap to have a sub do) then you will have a lot of progress at a lower cost.
As far as alternative stuff goes, we've done a decent amount of it in our house and it's actually cost effective and pretty cool in a lot of ways. My dad did a concrete counter top in the upstairs bathroom and it looks bitchin (cost nothing). House was built on a concrete slab, so we just did a finish on the floors. In our kitchen we did a quartzite backsplash and countertop for basically $70 in actual stone, looks super unique and badass - but it was extremely labor intensive. We're entirely off the grid too, running the house off a solar system and propane tank (septic, well). Make sure you get an adequate sized system though or you will be hating life (or just adjusting to not using much - something you do get used to).
PowderHound and TreeNinja