Thanks to all of you for your help. Actually, I don't mind paying for an interview. It's just that I don't have unlimited funds (I'm just barely able to afford the average fee for a doula in my area), so when I felt uneasy about some of the doulas who charge during the phone conversation I felt that maybe they wouldn't be my first choice to interview. I also felt uneasy about a doula who didn't charge for an interview, and chose not to schedule an interview so as not to waste her valuable time. Or mine, I suppose. Then again, I also feel like I don't want to judge anyone to quickly. Sometimes you don't really know until you meet someone.
I'll be trusting my gut mostly on this one. I'll be interviewing a couple of doulas whom I felt great about during the phone conversation. I may call back one that I felt somewhat uneasy about, because I do know that she was in the middle of a birth (taking a break) when she returned my call to speak with me. And she sounded as though she were tired or preoccupied, with good reason. (There is one doula I won't be calling back, because she was eating while she was talking to me. I hate talking to people on the phone and listening to them chew in my ear, and I can think of no good reason to eat while speaking to a potetial client on the phone. It's very unprofessional. I'd rather she wait another hour or day or week to call me back at a time that's better for her.)
Thanks again for the advice and opinions. It's helpful.
michelle