We'd have to know this before we could figure if it's a good deal.
It's probably not something you'll make any money on if it's a neutered ban-era naked muzzle barrel with the bayo lug removed and a semi BCG. Also, the trend right now seems to be flat top uppers and lightweight 1/7 carbine barrels. Sure there's the exception but that particular combo isn't exactly desirable right now.
ETA: KAC RASs sell for so cheap on the EE that it's not even worth doing it for that.