Mine with serial 288430 left the factory in October 1917, so I'd guess yours to be sometime in 1918. The grips would be the style that has the large gold medallion at the top, and they will not be cheap. Keep an eye on Ebay and Numrich, maybe a set will pop up. You could also sign up at the S&W forum and ask if anybody has some for sale.
Edit to add: Collectors, and the Catalogue of S&W, refer to that gun as the "Model of 1905, fourth change."