There is Federal money available for acquiring, restoring, and developing historic properties, and there is, more than likely State(if you want to call DC a state) money available as well. Before you do anything else, talk to your Folklife/Folklore friends as the Smithsonian--there are people there who know exactly what you need to do, and ought to be able to help you and support you--this is, after all, right up their alley, in their own backyard--

You should look at this as an opportunity to acquire a historic building and to expand the scope and impact of the association--

Two suggestion for raising actual cash:

is to have a "rent party" asking local businesses(restaurants, BBQ places) to provide the food, you have the entertainment--

Put together an assembly show for schools with the musicians, and donate the fees(they make good money for this stuff) and then have the musicians donate the money to the Association--this way, they can take tax deductions if they need them, which you can't do if you are just donating your time--