In terms of my medical costs and co-pays, hospital fees, etc. ... it was about $800 with my insurance, the whole kit and caboodle. Not too terrible when you compare it with surgeries or emergency room visits. This covered all of my prenatal screenings, tests, ultrasounds, the birth, and the hospital stay - and I was a high-risk pregnancy as well, due to having lupus. I had drugs during my birth, but not an epidural.
As far as the doula ... I have no idea as I didn't use one, but I hear they're pretty costly. They're not usually covered by health insurance either.
I think one of the most important things you can do is find the right OBGYN for you if you don't use a midwife or doula. The first OB I went to rubbed me the wrong way, so I found a new one. He doesn't push C-sections or inductions, or anything you don't need. He was fabulous, non-intrusive, no BS, and listened to whatever I had to say and gave me an honest answer for everything. He wasn't into scare tactics either (no unnecessary screenings just to have you worry about something.) So yeah, there are some good OBs out there. You just have to shop around if that's an option.
And if you don't want a C section ... best way to avoid one is to not have an induction if you don't need one. That's what my doc told me.
Now the costs when you have a baby. I breastfed for 13 months, so no formula here. I also cloth diapered (compare $1800-2500 for sposies over a child's diaper stage to $200-300 over that same stage for the cloth setup. Yes, washing is involved, but for the costs and the elimination of a lot of waste, it was well worth it.)
Good luck, whatever you decide! It's an awesome experience.