One of my neighbors is LE. We're really just acquaintences, but our kids play together, etc.
I gave him a call last night and told him about the email. He said I shouldn't do business with the person (obviously). He also said that there's really no point in reporting it, either. Until I actually deal with the guy, exchange money or guns, bounce a check, etc, no crime has been committed, and there's nothing to report.
He said that even if I did get scammed by this guy, it is unlikely that local or federal authorities would devote any time or resources to the case, as in the end it will most likely be a foreign national with extremely limited exposure to US law.