One place to look for doulas is through DONA, their training/certification network. Prices vary a LOT around the country, and even in a local area. I've heard of upwards of $2000 in NYC. In this area (southeast Michigan) I interviewed doulas ranging from $300 to $800. Most will also work with you on a sliding scale if money is a real issue.
I was thinking about this last night and wondered if you've had a chance to talk with your doctor about his philosophy on induction. The thing that struck me as most bothersome about your phone conversation is the statement that the doctor views you as "almost done" at not quite 37 weeks. Sure, babies come that early all the time, but if your little guy decides to hold on until 42 weeks you're still 5 weeks away, and I certainly wouldn't call that "almost done". I'm just wondering if he's the type to normally hurry things along as you approach 40 weeks, using that as a deadline, rather than letting things go post dates?