i can only wager a guess that it is either a used gun that he is needing to get rid of, or a build that he did himself. but again, that is just a guess. for that price, i'd be VERY suprised if it were a CMMG factory gun.
one caveat, i do believe they've been selling a cheaper line of guns, but they aren't the quality of course of their higher end line. not even sure they are built with chrome lined barrels.