I imagine it varies from manufacturer to manufacturer, as it is their requirement to protect their local dealers. In the NY tri-state area, the territories could be a lot smaller than in the midwest, too, due to the number of dealers in the area. You could contact the manufacturer involved if you're really interested.
Definition of Local Dealer
Oftentimes in an Audiogon/eBay ad from a dealer, you will see the phrase, "only offered if no local dealer", "support your local dealer", or similar verbage. Question: What constitutes a "local dealer"? One who is located in the same (large) city as you? A city 10 miles away? 50 miles? 200 miles? What is a reasonable distance/travel time? Does each manufacturer have its own definition of "local dealer"? What do y'all think?