Welcome to the Forum! Some pictures would definitely help with valuation because condition is everything. Your revolver's finish (blue or nickel) plays a big part in the desirability and value of a revolver, as does the type and condition of the wood stocks (grips). Do you have the original box and tools with your revolver? The early 4"bbl. .357 Combat Magnums (pre-Model 19), like the .44 Magnums (pre-Model 29), are quite valuable revolvers because they were only introduced about 2 years before S&W began using and stamping Model numbers in lieu of names. If, as you say, the condition of your revolver is really Excellent, then the value could easily be $1800-$2K for the revolver itself, and perhaps $2500+ with original box and tools.