Well, in San Fran, I guess the monthly income would just barely cover a mortgage! lol
I charge from $2000-3000 a birth and I usually have anywhere from 1-3 a month.
My state license is $2000/year
I spend, on average, about $2800 a year on supplies
I have an office, which is another expense
My gas for my car and car repairs is outrageous!
I pay for an assistant at all the births, which ranges from $150 (my apprentice) to $350 (when she's not available for whatever reason) per birth
I pay about $1400 a year in advertising, between local papers and the Yellow Pages
For office supplies, I spend about $600 a year
For conferences and continuing education and my state midwifery organization dues, I spend about $500 a year
For other misc expenses (like food when out at appts, etc), I spend about $600 a year
I also have other expenses, like TAXES, my cell phone and pager and my accountant, my website hosting and stuff. I'm sure there's more, but I don't have it in front of me.

All these things add up. I also have set my fee to enable myself to do some births for nearly nothing, so the my income does vary.
I can't speak for other midwives, but if done right, there's no reason why you cannot live on a midwife's income. However, just like any other profession, I earn my money - every bit.
