Dunno where you're from, but if you're going to live by yourself, I was told to be prepared to pay $1000 minimum. Now, there are cheaper options: rooming with people in a house, living outside of D.C. and commuting. But I wanted to live in D.C. proper and not in some basement where the sun don't shine.
Trust me, $845 is about as cheap as it gets for something reasonably safe.
I paid $700 in Seattle for a studio in the Capitol Hill area which was also considered pretty cheap.
The other thing to keep in mind is that hospitals are paying you more for the cost-of-living. As a new grad (well, until this August when I finish up my first year!), I'm making $60k. I've heard that can go up to $70k in NYC.