Hi, I live in Pullman :)
We will have medicaid (or whatever your state's version of that is) for healthcare. Is it possible that any of these states would cover a homebirth? The midwives here can have a midwife from Spokane come down who can accept Medicaid. This is what we are doing- it sounds like it covers about $1500 of the cost. So we're going to be left with about $1000 out of pocket. Here is the midwife from spokane who can take medicaid - http://www.bloomspokane.com/provider-directory/profiles/cathy-weston/
Are there any good charter schools in those areas? Maybe Montessori or Waldorf? Or a good homeschool community? There is a Montessori school here in Pullman, I don't know how old it goes to. No Waldorf here, but there are many homeschoolers. On facebook there is a homeschool group for the area you can join, also a co-op.
In California we have the option of signing a philosophical exemption for vaccines. Is it like that in OR/WA/ID? For Washington and Idaho yes, Oregon no. http://www.ncsl.org/issues-research/health/school-immunization-exemption-state-laws.aspx
How about cost of living? Could we find a 2 or 3 bedroom place to rent (with a yard or property) for around $800 or less? Yes you should be able to. But since this is a college area, if you try to rent at the beginning of the semester you might have a hard time. It would be better to come a little early or even at the end of the semester when everyone in town is moving out. We're in a 3 bed, 2 bath and our rent just went up to $860. If you find a house in one of the towns outside Pullman/Moscow, things get crazy cheap. http://pullman.craigslist.org/search/apa?query=&srchType=A&minAsk=&maxAsk=800&bedrooms=2 Looks like there are many options right now for under 800. If you come during the summer you'd probably get a good deal because so many people don't live here in the summer.
Personally I think Moscow is more hippy/natural living friendly. Both towns are very accepting - no one cares about breastfeeding in public or really any natural living choices people make, and I have found quite a lot of people who live that way here. There are several MDC people who live in the area. I probably just want to live in Moscow to be close to the awesome food co-op they have. If you visit to check the area out, be sure to check it out!
Let me know if you have any other questions, I have been compiling resources for natural living in the area for a couple years now because I want to make a natural living/parenting website directory for the Palouse area :)
edited to add: I don't know if you know or not- but Moscow is only 6 miles from Pullman, so you can easily live in either town and go to the other town's university.