Model 29: The Silhouette Caliber:.44 Magnum. Double-action revolver. Built on the square butt N target frame with three screws; 10-5/8” ribbed barrel with adjustable four-position front sight, the adjustable rear sight a black blade with a narrow and deep notch; 6-shot fluted cylinder with a nominal length of 1.69”. Checkered Goncalo Alves target grips with S&W medallions, N target frame with 10-groove serrated backstrap, .400” target trigger, .500” target hammer, shrouded extractor. The first prototype was serial number N905892 and was sold at auction on July 24, 1996 by Butterfields. Special presentation case available. First guns had “N” prefix serial numbers that quickly changed to the three-letter serial prefix. Guns with pinned barrels or counterbored cylinders have not been substantiated. Produced c. 1983 – 1991.
Supica, Jim; Nahas, Richard (2006-12-20). Standard Catalog of Smith & Wesson 3rd (Standard Catalog of Smith and Wesson) (p. 186). F+W Media, Inc.. Kindle Edition.
I don't think $900 is unreasonable if the gun is in good shape and it's what you want, not a bargain, though, in my opinion.