Yes -- doulas care can be an excellent source of a more affordable doula. They provide free doulas for women who meet their income guidelines and an inexpensive doula for women who don't. The trade off is that you don't get to pick who is matched with you -- I think you can veto a particular person if it is a really bad match, but you can't interview a number of women and pick the one you like.
The doulas who advertise in the directories are often the most experienced of the bunch and the ones who are doing this as their primary work. So, they are the most expensive as well. But there are probably more than 100 doulas practicing in Michigan now (sometimes it feels like there are more than 50 just here in Ann Arbor
). I see a lot of business cards in some of the places I frequent, like offices where childbirth classes are held, natural food stores, pediatricians' offices, or kids' play spaces. Some of those women will be newer doulas.
Sometimes a newer doula can be more passionate and if she is less busy, more energetic or provide more service. It isn't always best to hire the person with the most experience.
I think there are a lot of doulas on here too, but they can't advertise here or offer to help on the public part of the board without getting in trouble. I think if you put out there what geographic area you are looking for, you might get some helpful PMs back.