That's interesting because the place I bought mine from here in SD does about the same volume monthly as the Drone+ guy told me his stores do in a variety of urban areas, so I think the sales revenue numbers. I think I am a typical quad customer in that I researched the
ba-jesus out of them online and then wanted to see and purchase mine from a brick and mortar in my area because I wanted the support that would come with that (questions, crashes, repairs, upgrades). I would have never gone to a "RC shop" for the quad because I was not an RC enthusiast. The volume these stores are reportedly doing is about what I would expect, with a 26% gross margin and 11-13% net margin...not bad numbers.
I believe people who are going to buy quads are going to, in most cases, be exactly like me: first time RC aircraft purchase, ready to spend for the high-end product, and wanting to be able to come back to a physical location to have service, questions answered, etc. That was my experience in my purchase. I sales taxes are what they are, and I really don't think it hinders retail business at all.