Mysha, I'm thinking you mean B&B in the European/UK sense -- a room in someone's home -- rather than an American B&B, which is in general a rather posh, small hotel tailored to romatic getaways.

If that's so, budget hotels will probably be more in keeping with your budget than our B&Bs. Also, 1've known college campuses to rent out dorm rooms during non-school periods, which your time period would be. Whether Georgw Washington University has such a program, I couldn't say; I'm from the Wild, Wild West where things may be different.

Best of luck! And the whole DC area is chock full of wonderful musicians. You should have a grand time.