Something I found on Facebook
Is that THE chair, or a replica? Looks pretty damn good either way.
Its gotta be a replica, Sigorney Weaver mentioned in the dommentary on the blu-ray, she got to take home an arm and recently found it in her drawer. But it is cool looking
Excellent prop! I wouldn’t have thought of making that one.
It could just be an old photo of the prop.
the arms of the original are wider, other then that it is pretty accurate
like I said before. if you compare the screenshot from the actual movie, and the top photo of the “prop”, its not the same chair. the arms of the chair in the film are wider then the arms of the chair in the top photo. is there an echo in here? the monster arms might be the same from the film, but the chair is not. the chair in the top photo is likely a real chair that the arms were stuck into before or after shooting to show what they would look like during the grabbing scene. on that site there is a photo that shows the chair in the film would have been fake or hollow to allow for the “monster” actors to reach their arms up through to grab her. either way, the chair in the top photo is not the one that Sigourney sat in for the actual scene. now is when you nerds start to flame me.
From the same site:
A bit hard to tell, but that photo looks more like the one in the photo as opposed to the still from the movie. The movie still appears to show the left arm coming through the middle of the chair arm, as opposed to the inside right of the arm, but maybe it’s all from multiple shots, or it could all just be distortion from the film width?
The chair in the above photo has no arms. Most likely a “Stunt Chair”. 
The guy probably just wanted to display the arm props and picked up a similar chair.
true, but NHVenkman said Sigourney owns one of the arms, maybe they had doubles for each arm in case one was damaged
OHGOD I want that chair! I could never have company over again. Excellent replica :3
What about this chair? 
it’s the one for the GB slot machine from IGT.
Its got 4 speakers up top that blast in your ears, and a built in sub woofer under the seat!
I foresee a new office chair for Vincenzo. The speakers seal the deal.