stamped or milled? A true preban will still have a folding bayo and pistol grip, muzzle nut or slant brake, there were also the MAK 90s which were an attempt to get around ban no bayo lug not threaded muzzle and thumbhole stock.
Value is going to depend on alot more info than ya have posted, what are the markings etc?
A MAK 90 will run ya around $400 in like new condition on a stamped reciever a milled reciever can almost double that and a true PRE-BAN up to $1200 depending on how its equiped...