Just chiming in on what I've encountered so far.
I too had my first baby at NWH with the midwives of WHA. With #2 I knew I wanted a home birth (I'm 31 weeks now) - my hospital birth was fantastic too but I have zero desire to make a trip there and stay!
I saw Valaree at WHA through 19 weeks while I researched home birth midwives. She knew from the beginning I was planning a home birth and was incredibly supportive. I elected to use them for prenatal until that point to make it a little easier on myself -- that office is very convenient for me in terms of work and that bought me some time to navigate the home birth midwife world without worrying about insurance (although I understand it's usually fairly easy to get insurance to cover a CPM / DEM for prenatal). WHA definitely does not backup homebirths.
My homebirth midwife uses a billing service that has been really helpful to me in terms of navigating billing insurance. I've also put some money into a flexible spending account to cover some expenses like the tub rental fee. My midwife charges approx. $3200 and all signs seem to indicate my insurance company will cover this as out of network, leaving me to pay a $450 deductible. I have Cigna PPO which is apparently one of the better plans to have in MA in terms of getting a home birth covered - there are a lot of women who have succeeded with them. That said, it's still pretty sketchy - they claim to only cover homebirth with a CNM with OB backup (impossible in our state). At this point I'm just hoping for the best that it will be covered and have accepted that it may not be.
I interviewed five midwives - all charged around 3-3500 and all were in the greater boston area.
I was kind of surprised and disappointed by the process of finding a midwife to attend my homebirth - it's nothing like choosing a CNM from my experience where my focus was more on the birthing facilities, size of practice and just a personal impression. I got a fair amount of unsolicited personal anecdotes thrown at me while interviewing homebirth midwives and advice that in the end felt more about politics. It can be very confusing! Having a few people I knew I could trust to bounce information off of was really reassuring for me.