I'd like to try and help, but your question is a bit vague for me.
The nickel Chiefs Special you're looking at could be anywhere from
1958 to 1976 (or from 1966 to 1988 if it's a Model 36-1 with a 3"
Heavy Barrel).
What's the serial number or at least the series? Which thumbpiece
does it have? Are the stocks original, and do they have a diamond
around the screw and nut escutcheons? Round or square butt?
Typically a nickel Chiefs Special brings more than a blue one, all
other things being equal. How much more? Now, there's the
question. Much has to do with the buyer (i.e., how badly do you
want it?).