Unless you specifly which model of Maadi rifle you have it is impossible to tell what it is worth.
Pre ban Maadi rifles were only imported by and stamped on the left side of the receiver "STEYER SECAUCUS,N.J." If not stamped this way the rifle is a post ban rifle.
Post ban rifles were imported by several importers.
PARS INTERNATIONAL CORP. Lousiville,KY imported Maadi rifles from 1993-1995.
Imported 2 models the ARM and RML both with thumbhole stocks. The model ARM had a 16.34" barrel length with a threaded barrel with a muzzle nut tack welded on. The model RML was imported with 16" and 20" barrrels with the threads turned off the end of the barrel.
ACC/INTRAC Knoxville,TN imported Maadi rifles from 1993-1995
Imported models the ARM and RPM both with thumbhole stocks. The model ARM had a 16.34" barrel length with the end theaded with a muzzle nut tack welded on. The model RPM had a 20" barrel with the end threaded with a muzzle nut tack welded on. The 1993 imported RPM rifles came with a bipod attached and later imported ones didn't.
Century Arms International or Century International Arms- Saint Albins,VT or Saint George,NH imported Maadi rifles from 1997-1999. They also assembled Maadi rifles from imported parts in 1996-1997.
Imported models were,
MISR with a 16" barrel with the threads turned off the end of the barrel with a thumbhole stock. It was imported in 1997 till this ruling by the Treasury Secretary.
http://www.atf.gov/firearms/assault/treasrelease.htm
After the ruling the MISR-10 model rifle was imported that were the same as the MISR except it could only use 5 or 10 round magazines made just for it to comply with the Treasury ruling.
In 1999 the MISR S/A rifle was imported without triggers,sears,pistol grips,or hammers. US parts were added to comply with United States Code Title 18,Chapter 44,Section 922,Paragraph (r).
Assembled in the US rifles.
The model MISR-90 rifles were assembled by Century Arms from Maadi receivers and Chinese MAK-90 parts kits. They bought 1000's of MAK-90 rifles that were disassembled and had the receivers distroyed after the import of Chinese guns and ammo was banned in April,1994. They imported Maadi receivers that had both trunions,rails,trigger guard,and mag catch installed. The first ones due to the Maadi receivers having a AKM front trunion that has a opening for a barrel with a 23mm barrel shank required a sleeve to be added to the smaller 19mm barrel shank of the MAK-90 parts kit barrel. The later assembled MISR-90 rifles used the Chinese front trunion from the MAK-90 parts kits and a Maadi receiver imported without a front trunion installed. Besides the rivets being loacated in different places on the trunion/receiver the early MISR-90 rifles have the model stamped on the left side of the reciever where the later rifles have it stamped on the barrel.