My 2012 blue book lists a National Match model that they claim was built 1988-90 and had Herrett wood stocks , Bo Mar adj sight and specially fitted frame and slide with a NM barrel and bushing.
$565 95% , $650 98%
Somehow this doesn't match real well with your gun ?(other than the NM stamp)
Standard model blue or parkerised
1985-90
98% $360
95% $330
90% $300
retail list was $454 in 1990
These were ok guns but finish was only so so and they never really commanded higher prices except for some special models . Folks who are collecting 1911s do Colts or military models , I can't see any value except as a shooter .
Do you think this gun was just not used much or was it refinished? Does the barrel shroud and lock up lugs have much/any wear.
Has the throat been polished? ( I might guess a us built NM model might be tuned up a bit but I don't really know .)
What does it have for sights? I would also think a real NM gun would have something better than the tiny GI type but again I don't know.
The "Blue Book" is usually pretty good with models and dates but maybe if they offered a NM model in the 1988 catalog the factory was playing around with them before that.
Seems to me if the gun was really built to NM type specifications with a good tight barrel , tuned fit and trigger and something decent in sights it would be worth $500-600 or a bit more as a quality shooter.
If it is just a SA shooter that has a plain factory trigger and barrel with GI type sights that somehow had NM stamped on the frame its a $350 shooter
One mans opinion , take it for what you paid for it