Overall FFX Station is not so expensive, there are a few of the larger houses close to or over 2M, however, most are in the $750k-$1.5M range.
Doctors, Lawyers, Lobbyist, Business Owners, Federal Employees can all afford these houses. Some cannot afford these houses but live there with very little financial cushion.
The problem with FFX Station IMHO it is in the middle of no where. Sux to get to DC, Tysons, Falls Church, Fairview Park.
I guess if you work in Springfield or Annandale is might be convenient.
Schools are ok I guess.
Here is and example of what you get for $1M, no bushes on 5 acres!
http://www.zillow.com/homes/for_sale/Fairfax-County-VA/51890704_zpid/1694_rid/any_days/38.828876,-77.139988,38.687519,-77.475071_rect/11_zm/