Try the discount clothing store in Brentwood shopping plaza with the Giant and the home Depot. I forget the name but if you are facing the Giant it will be towards the end of the strip on your right. It has been awhile but almost every time I have been there they are clearing out local sports gear and I have come away with something from the Nats at a fraction of the price. They have Caps, Redskins, DC United and Chicago sports too.
Nice! That is a very surprisingly good Giant.