Grabagun.com
I just completed an online firearm purchase using grabagun.com along with a local gun shop (Virginia Arms in Manassas) here in VA that I used for the transfer.
I must say this was one of the quickest, easiest, and most legitimate transactions I've ever experienced - hats off to both grabagun.com and VA Arms.
The internet is your friend, so use it wisely and you'll discover that both grabagun.com and VA Arms are highly rated in just about all areas.
If you want the best price, a painless process, fast shipping, and regular communication throughout the process, then grabagun.com has my vote hands down.
If you live in the northern Virginia area and value good service, down-to-earth knowledgable staff, and a great selection - Virginia Arms is the winner.
Hope this helps.