What type of pricing do you get when you use the national sites like the ones listed below that all offer help with pricing by region/zip code:
If it were me, I'd use each site to get a local selling price, then add them all up and divide by the number of sites that were used...this would give a great "average" selling price to work with that is representative of your local area.
Edit: oops...just noticed your location is
NoVa...don't know if that stands for Nova Scotia, Canada, or North Virginia, USA
hopefully the sites above work for you...if they don't, then find similar sites that work for your part of the world.