Brasserie Beck, Granville Moore, Belga Cafe, The Sovereign will probably sell you bottles from their selection. But if you cant find what you want there

Rodmans, MacArthur Beverage, Craft Beer Cellar, Sherry's, Harry's Reserve, Magruders, and Calvert Woodley all should have options.

I dont know outside of the restaurants how many of them sell singles.