As Cindy says, you have a lot of choices in the Lorton area. A little bit closer to DC is Burke, with a lot of affordable townhouses, and it's a nice area, too. Commuting from Lorton into DC or Alexandria can be a bit of a hassle...though plenty of people do it. Just take a look online to get a general sense of prices, the communities, etc. Then contact some agents in the area. (I'm with a firm with offices in Lorton and Burke, by the way.)
P.S. The posting recommending the Chesapeake Virginia property? No where near Lorton. In fact, no where near Northern Virginia.