And don't confuse factory demo with gray market. Store front business have products available for customer touch and feel which may be fondled, dropped, dirtied, otherwise used but aren't preowned and hence keep the full factory guarantee. In many cases, they are sent back through the factory service program to assure proper operation.
Gray market comes in several flavors. When a product is sold in country A and it is taken to country B for resale by someone other than the factory distributor, it is gray market. The product may or may not be manufactured with slight differences for country A, even carry different numbers than products provided for country B. Companies discourage gray market schemes as the circumvention costs profit, distorts sales figures and wasted time dealing with abnormal situations so a penalty of warranty loss is often imposed. Warranty complaints on gray market products are always statistical higher than for regular stock. Sometimes products require aftermarket modifications to meet country standards, a cost not figured into buyers initial decision.
Both schemes are activated by the human greed instinct to get more than you pay for. Most of the time it works, but not always. Buyer beware. My first Nikon outfit of one month's salary was bought mail order from Switzerland when I worked in Brazil. No problems. At one point the San Francisco Nikon dealer had the whatsis fixed for me gratis from Nikon.
Just know what you are doing and the risk for what could be a very small savings and the long term rewards and satisfaction which comes from dealing with a local store.