A few times when I was in the store we would get into a conversation about the impact of online sales on B&M retailers -- it definitely has affected them and now Calumet is the latest casualty. The sales staff at Penn/Calumet were well aware of how many people would come into the store, browse, then ask to see various cameras or lenses, then after taking up quite a bit of time would go home and order the item of choice online. That's not right but a lot of people have done and continue to do that, saying that they want to save money on taxes (which one is supposed to pay anyway) or that it is more convenient to have something shipped to them, etc., etc. I have always purchased as much as I could locally, and when I go into the store and take someone's time and pick his or her brains about various aspects of an item, I expect to then purchase that item or a similar one then and there. The few times I've ordered camera gear online has been when whatever I needed was simply unavailable locally.
What's left in the DC area? Ace Photo in Ashburn, VA and PhotoCraft in Burke, VA. Embassy Camera in DC (related to PhotoCraft) and Service Photo in Baltimore. Those are the ones of which I am aware, anyway. I've shopped at both Ace Photo and PhotoCraft -- each has great inventory of both professional-level and consumer-level gear and good prices.