It depends what you mean by early. You can beat the traffic in the morning. The problem is more in the afternoon/evening (you'll work enough that you'll want to get home when you get the chance and waiting for rush hour to end is pretty hard).
Off the top of my head, in the DC area, you'll potentially rotate at NNMC, WRAMC, Malcolm Grow, Fort Belvior, Washington Hospital Center, St. Elizabeths, and various ED's in DC and Baltimore.
Unfortunately, that price is about right for the closer communities. We rented a house in Kensington that was probably in the $350K range (and most have gone up since).
If you want to own a home for less than that, you'll probably have to live further out. I loved the short commute, especially post-call. I just wanted to make sure people weren't just timing the drive to USUHS but factored in these others. Most rotations are at NNMC and WRAMC but not all. There were members of my class who lived in Gaithersburg with their families and decided to do out of town rotations rather than face driving to some of these.