You can make incredible deals by buying leftover units that way. The dealers really want to move them. The only issue to be considered is resale value. Keep in mind that by buying a unit that technically already has some age (according to the books), you have lost some value. The loss can be offset by paying less.
For example, if you go to resale or trade a 2013, it's worth less than a 2015, even if both units are brand new. When people shop for used, they consider dates. Banks and insurance companies do, too.
It used to be that some banks would not finance used units older than X amount of years. That may not be the case anymore, though.