32nd edition of the Fjestad Blue Book says $450, but a search of recently completed Gunbroker auctions shows that the going rate seems to be ~$650 in this condition. This seems consistent with the increase in value of other .22LR Smiths; I bought a 98% M18-2 for $500 several years ago, but I would probably spend ~$700 to buy the same gun today!
One footnote: the Standard Catalog of S&W indicates that a distributor exclusive was made in 1991 only with a 6" partial-underlug barrel rather than the standard full-lug barrel. Neither the SCSW or the Blue Book indicates what premium this model carries- perhaps because the sample size is too small- but my "SWAG" estimate would be ~$200.