Blue Ridge Arsenal! My friend works there. Their collection is amazing. website:
http://www.blueridgearsenal.com/
And yeah the NRA is cool too, and they have a range in the basement.
Damnit, the Galyans in Fair Lakes HAD guns but ever since they were bought out by Dick's Sporting Goods they got rid of them. One of the leftover sales guys there gave me a card for "Furr Supply Co." Supposedly cheapest gun prices in the area, but I haven't personally checked them out yet. (703) 620-0441 if anyone is interested.
Krav Maga is taght at three schools in Fairfax County according to their website:
http://www.kravmaga.com/virginia.asp TONS of Tae-Kwon-Doe places. I did Mt. Kim in Chantilly for years.