I was thinking of getting a nikon d750 kit from someone posted on craiglist. The owner claims he has the original receipt from B&H, together with warranty cards. Is there anyway to verify that it is US version, instead of Import, both for body and lenses? Also, what are things that I can check on the spot to make sure the body and lenses are in good working condition? Should I get both parties to sign Bill-of-Sale or something, or is there anything else I can do for my protection?