The value will depend on a number of factors. Condition of the firearm, length of the barrel, type of metal (blued steel or stainless steel), original or aftermarket grips and if the box/papers/owners manual are included. As of early 2009 a Service-Six could be found for about $300 to $500, depending on the items listed above. The short barreled versions are currently in demand and generally bring the highest price.
100-300 or so
50-500 usd
Depends on what shape its in but $250-$300 is a good price if its decent.
100-300
100-400 USD
100-300
100-1000 USD
200-1000 dollars
150-300 USD
75-260 or so
100-500 USD
50-300 usd