What Irene says is true, too -- lot's of variables involved. It is also about supply and demand. Right now 22554 (Stafford) has about a 5 month supply of homes for sale (compared to 1.7 months supply in Fairfax County and 2 months in PW County). That means that Stafford is still a buyer's market (big supply/not much demand) and the northern counties are now experiencing a seller's market (in the lower price ranges which is currently Stafford's average price range).
If you'd like more specific statistics relating to your area, I've got 'em and I'm happy to forward a free, no obligation report to you so you can feel secure in the knowledge that you have the most accurate and current information concerning your marketplace and neighborhood.
Happy to serve.