I can't speak to the asking price without knowing the condition of the rifle. $900 seems a touch high unless it's in good shape. But given the still current, high anxiety over semi-auto military style rifles, and the fact that these rifles are uncommon to begin with, and not imported any more, you may want to snag it.
My NHM-91 was imported in 1993, but I bought it used about 18 months ago, just before the CT school shooting, for $499. It's no tack driver, about 5" groups at 100 yards is normal with steel, though I can get better with hand loads. I put an AMD-65 brake on it, and it's very fun to shoot, bump-fires easily, and I've never had any kind of malfunction with it.
You'll get some stares at the range because: 1, it's the 'enemy's' rifle of choice; or, 2, because a lot of AK guys are not familiar with the NHM-91, and sometimes make comments about the barrel length.
Tom