You're basically talking about a collector shop. There are plenty of them around. Some do business the right way, and others don't. But most of them follow this business model:
Sell toys - Not just Star Wars, but other "hot" lines that collectors are into (DC & Marvel Superheroes, Transformers, GI Joe, McFarlane)
Sell higher end collectibles - Companies like Gentle Giant, Sideshow, Master Replicas, etc
Sell comics - Comic books and magazines bring in a good deal of weekly traffic
More advanced stores will also launch an online store to complement the brick and mortar store.
As for your stock situation? You have to have a number of different sources. If you're going to do things on the up and up then you start up accounts with suppliers: Hasbro, Diamond, Gentle Giant, Sideshow, DC Direct, McFarlane, etc for new stock at wholesale prices. You can also sell older and vintage items, but that's going to be at market prices.
What a scalper will do is try to buy stock at local stores for two purposes: create artificial demand locally, and markup the items so that he's going to make a profit.
As for making a business like this work? It's like any other small business.
-Startup money. You need to get enough money together so that you can establish your accounts, get a location, stock the store, pay any employees, etc. And you need to be able to operate long enough that you start generating profits.
-Small business models usually do not turn a profit for 3-5 years from initial investment.
-Good location. This can make or break a business. You want to be in a place that's got a good ammount of traffic going by, but isn't going to break you on rent.
As for specializing in Star Wars? In theory it sounds good, but you might be limiting your potential client base. And that could doom your store.