They came and they went in the 1980s and 90s. Opening a sports card shop was one of the most popular ventures around during an era when everyone was on the bandwagon.
Many didn't keep up with the arrival of eBay and the revelation of overproduction. Those that had built a strong core of customers and treated them right did OK, though.
A.J.'s Sport Stop in Vienna, Virginia opened its doors in 1980--even before the arrival of upstarts Fleer and Donruss. The shop isn't "brick and mortar". It's a double wide trailer, but stocked with plenty of inventory.
They're still going strong these days, thanks to an influx of young regional stars. There is good news for the industry, too. The owners told the Fairfax Times in this local feature article that about 1/3 of their customers are under 25.