Dulles is not really D.C., but I don't want to nitpick on your parade. If you're moving near me, I would prefer you stay as far away as possible. Herndon really is not a ghetto city, but I'm not going to say it's completely deprived of urban blight because I'm sure some Herndon resident might say some neighborhood sucks more than others.
A good rule of thumb is that if you want to live in a nice neighboorhood in the DC metro area with all the amenities, you can expect to pay upwards of $850-$1,050 per month for an apartment. That's the cost of living around the damn city.